W215 Battery Drain

Discussion in 'Electronics' started by rk100, May 15, 2015.

  1. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Hi Ray,

    Thank you for the updated information of which I’ll go through with you now to clarify the outcome of the test results. My apologies for only just coming back on to the forum but we only arrived back in the UK following our holiday on Tuesday evening and I have been busy with other things over the last couple of days that needed to be done. We will go through the points you raised on a step-by-step basis here Ray to save any confusion and I am also conscious of the fact that I don’t want to overload you with tedious tasks that follow on from these tests.

    Lets look at Fuse No.78 first Ray, which is directly connected to circuit 30 and is a permanent live circuit from the vehicles battery via a 60-amp fuse. I note from the figures that you provided prior to you removing the fuse anyway that the parasitic drain levels are still consistent with earlier readings, however, when you isolated this particular circuit by removal of the fuse the figures dropped off from 0.040 amps (previous lower figure) to 0.030 amps, some 0.010 amps differential but were still fluctuating. The 0.010 amp drain is consistent with what it should be here Ray as the circuits that you have just isolated and removed from the equation are the EIS, (electronic ignition switch) CCM, (cruise control module) ATA, (anti-theft alarm) ECM (engine control module) and the SCM, which is the steering column module. These are five of the major modules on the car anyway and the parasitic drain level if divided equally between these modules is pretty much the same as what they should be anyway, so there appears to be no issues whatsoever here.

    The overall removal of all the other fuses that you noted prior to the removal of Fuse No.78 did not essentially materialise any noticeable difference in parasitic drain changes when they should have done, albeit they would have only been minor in comparison to the above circuit, but all these modules are on the MOST optical bus network anyway and it may be the case that because the parasitic readings are fluctuating so much as its difficult to determine exactly by what amount they did drop, if any, unless we have a stable reading to compare them from. We will also test the Audio Gateway Control Module very shortly which effectively “wakes-up” these modules to determine if this unit it is actually being switching on/off and not contributing the to the excess drain. However, on a more positive note, by disabling these modules proved out in practise that these are not contributing to the fluctuating figures, so that is good new anyway.

    Fuse No.60 is the circuit fuse for the rear window antenna amplifier module and only consumes 0.260 amps when switched on and is directly connected to the audio gateway control module and is one of the few modules that does not go in to sleep mode but we can do a systems check and measure the amount of current flow and determine if it is actually being switching off via the COMAND unit. If need be, then we can always eliminate these other modules on a one-by-one basis if we have to anyway. Time consuming as all this may be, I know very well Ray that you do appreciate that this does take time but sometimes this is the case with this type of scenario you have, I would sooner that you do it properly and correctly thereby removing any element of risk and/or damage to either yourself or the car. I don’t think people actually understand or even comprehend how complex a modern motor vehicle actually is. This antenna module (above the rear screen under the headlining) is also linked to the overhead control panel module and the overhead control panel module communicates with the EIS for key recognition and authorisation. I’ve already covered this area in some considerable depth and drawn some schematics and flow charts on this topic previously for one of our US members on here, have a look at the attached flow-chart below from that particular thread.

    As I have already briefly explained in my last PM, the keyless-go issue will need the current car keys coded to the module itself. Unlike the EIS module, where up to 8 keys can be stored at any one time, the keyless go module only has 2 key tracks and if this is the original keyless-go module, then the keys logged within the module will have to be erased by someone with a Star diagnostic machine and the new keys then coded in. This is why I said to you earlier Ray if these are new keys that you have then the previous owner should have had these coded in anyway. However, if this is a new keyless-go module itself, (and your keys are the originals that came with the car from new) then the keys you already have do not need to be coded on a Star machine and there is a very simple key-code (learn-in) procedure which you can follow and go through and it takes no more than 10 minutes to do anyway, but you would have to determine if the module has been replaced first. Check in all the service history, invoices and receipts that you would have got with the car. I can always guide you through the procedure anyway if need be, in any event, it’s not that big of an issue that can’t be resolved as and from your description above the module is active and functioning properly with the message “KEY NOT RECOGNISED” being displayed in the multifunctional display window.

    If it’s possible Ray I’d like us to just go back a step at the moment with regards to the Central Gateway Control Module. The initial figures that I gave you were 2.5 volts on both the CAN - High and CAN - Low circuits in its idle standby mode and 2.48 volts in its active mode with no date being transmitted; these figures can only be obtained and measured across both pin numbers 6 and 14 to ground in the J1962 diagnostic connector. However, your results revealed 2.43 volts in idle standby mode and 2.47 volts when in active mode with no data being transmitted. As I made reference to in my last post, is this an anomaly, well, the only way to find out now for sure is to check the system and see what the results are. Lets test the circuit out thoroughly here Ray and confirm either way its integrity and identify if the gateway modules transceiver has a short to ground or any other parts of the circuit. Follow the steps below exactly in the same sequence as I have written them.

    The Central Gateway Control Module is once again on circuit 30, which is a permanent supply voltage from the vehicles battery via Fuse No. 83 - (10 amp - red fuse) which is again located in the n/side of the dash behind the inspection trim cover. To do the following tests Ray we need to disconnect the vehicles negative battery lead and place it in a position away from the negative battery post.

    Now remove Fuse No. 83 from the fuse box so we can isolate the circuit back to the Central Gateway Control Module and then set up your multimeter to the read on the ohms scale only. Select the 20M range scale, as this is the only one you have on you meter to measure megohms anyway. Place the test leads in their respective jack plugs and attach your crocodile clip on the ground side. Now connect that to the parking brake aluminium bracket and measure the individual resistance values on pin numbers 6 and 14 again to ground. This is exactly the same test as we did earlier here for the voltage tests Ray, but we don’t want to measure the voltage again as we have already done that. What we are in fact doing here is measuring the impedance of the Central Gateway Control Modules transceiver (electrically isolated) to determine if current (short circuit) is leaking to ground or any other parts of the circuits.

    When you do take the measurements you should obtain readings of between 7M ohms to 9M ohms on both pin numbers 6 and 14, typically, they will be around the 8.5M ohms range. This value is based upon and assuming that your Central Gateway Control Module incorporates a Siemens transceiver, the earlier gateway modules had either a Phillips or Texas Instruments transceiver, which was rated at a lower impedance value and some were prone to failure. I speak from personal experience here Ray as several of our model vehicles had a very similar issue with this type of hardware transceiver from both of these manufactures, albeit our systems were used for an entirely different and alternative application process other than a gateway module, but still CAN bus related.

    The next test we need to do here Ray is to measure the current draw through Fuse No 83 - (10 amp - red fuse) as a “stand alone” test only. You do not need to set the car up as previously done so for the global parasitic drain tests, we are doing this test as a single test only and the vehicle does not need to be in “sleep” mode. If you wish, you can use the in-line bladed ammeter here that you bought from Maplins to do the test. Put the ammeter in place of Fuse No.83 and then re-connect the battery lead and then observe the current flow through the meter. It will initially be around the 0.080 amps range, give or take either side but it will be within the parameters of (0.078 amps - 0.082 amps) but on this particular gateway circuit it will drop out to zero amps after 15 - 20 seconds, similar time frame to the voltage tests we did earlier on the CAN bus, so you will have to be quick to observe it. To initialise and conduct a “time-out” test facility again, then either switch the lights on and off, operate the steering column adjustment by moving the lever or even move the seat forward momentarily, you can actually leave the door open for this type of test Ray as we need to use anything really that wakes up the communication module. If the current drain then remains constant, fluctuates and fails to drop off to zero amps following the time out sequence, then this is possibly where we may find a problem.


    [FONT=&quot]Continued on following post……………………[/FONT]
     
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  2. Dash1

    Dash1 Active Member

    Messages:
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    Joined:
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    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    It’s no coincidence here Ray but the current drain on this particular circuit alone when in its “standby” or “active” mode is not that far away from the fluctuating figure we are looking for. If you do find that there is constant current being drawn on this particular circuit or it is fluctuating then disconnect the vehicles negative battery lead and remove your ammeter from the fuse box (for the moment, do not put the fuse back in again) and with the ammeter removed re-connect the vehicles battery lead with your multimeter set to read amps in series with the battery and the battery lead and then measure the systems global parasitic drain level again.

    Ray, to put this in to some form of perspective and for information purposes only, then a 0.080 amp current flow across a 10 amp standard fuse represents a voltage drop of only 0.0006 volts, which is in fact six tenths of one millivolt, or if you prefer, 600 microvolts and you would not be able to detected it on your own multimeter when measuring voltage drops across the fuse. You really do need precision test equipment to work with voltage levels in the range as low as these; your own multimeter will only measure as low as 1 millivolt (1/1000) and will then show up as a zero reading if the circuit is working properly and not consuming excess current. Make a note of all the values and data and we can go from there. Ray, under no circumstances should you turn on the ignition switch with Fuse No.83 removed, so replace it immediately following the parasitic drain test, otherwise, you will have the SRS light come on and you will not be able to clear it without some type of diagnostic code reader capable of reading/erasing fault codes.

    With Fuse No.83 effectively removed and the ignition switched on the SRS module will not be able to communicate with the rest of the vehicles modules over the CAN bus network because effectively, you have just disabled the network by removal of the gateways system fuse. There are no other issues to be aware of other than this one here Ray, so be careful. This is yet again another very good reason and an example as I previously stated in an earlier post on fuse removal during these types of tests, it shouldn’t be done, but each to their own I suppose. 25 years ago it was normal practice then to pull fuses at random, but those vehicles never incorporated such sensitive and electronic devices as of today – today’s modern cars are extremely complex and an absolute minefield when it comes to electrical circuits and there is always one individual willing to chance it and pull fuses with little or no knowledge of the consequences of what’s going on at the other end.

    The next test here Ray involves checking the Audio Gateway Control Module, unfortunately, it would require a considerable amount of trim removal to gain access to the CAN transceivers input/output connections and this module is unlike the other module that I spoke of above. However, there are two specific tests here that we can do to confirm its integrity and functionality. The module once again is on circuit 30, which is a permanent voltage supply via Fuse No.24 - (20 amp - yellow fuse), which is located under the bonnet in the right hand side fusebox. It’s the 4th fuse down from the top right hand side as viewed from the front. Again, disconnect the vehicles battery and insert your ammeter once again here Ray and place it in a position facing the windscreen so you can actually see it when sat in the passenger side. When ready, reconnect the battery and then switch on the COMAND unit and monitor the ammeter, it will now go up to as much as 2 amps and settle down, leave it alone for a couple of minutes so as to get the best possible reading and then turn off the COMAND unit. As you turn the unit off, the current consumption will gradually start to decrease, would you time it out as it should now shut down completely within 90 seconds and the ammeter should now read zero amps.

    To do an alternative test in place of the ammeter test on Fuse No. 24, then you can also do a volt drop test over the fuse and monitor the results. You will also need someone to help you with this part of the test Ray, so maybe your wife if she has the time. When Ready, place your volt meter leads across the fuse as you have done previously with other fuses and then ask your wife to switch on the COMAND unit and monitor the voltage dropped over the circuit. It will initially rise to approx 0.009 volts and with the COMAND unit turned off monitor the time as it drops down to zero volts, again it should be the same as the current draw test as above - 90 seconds.

    The final test you can do here Ray is on Fuse No.60, again place your ammeter in place of the fuse and then turn on the COMAND unit, the ammeter should now read approx 260 milliamps (0.260 amps) and when you turn off the COMAND unit this current draw will drop off to zero amps almost immediately, there is no time-out facility to worry about here. Let me know what the test results are for all the above. There’s no urgency or the need to rush here Ray and you can do them all individually if you like to break the monotony of it all. My apologies for the lengthy posts but it is absolutely necessary that I do try and explain as much detail and as simply as is possible in an aid to guide you through this properly. I only start back to work the first week in September anyway, so I’m home most days (unless I decide to do a bit of fishing) until then doing something or other so I’ll pop on and off the forum from time to time to see how you are doing or if you have any concerns. I can’t emphasise this enough here Ray, but if you are not sure about doing something before you do attempt to do it, then please ask me.

    I’ve also drawn up a circuit diagram here Ray (see below) to help and assist in making it easier for you to follow the tests on the Central Gateway Control Module. Good luck and let’s hope these further tests produce the result we are looking for, if not, then we will carry on.

    Best Regards,

    Dash1
     

    Attached Files:

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  3. OP
    OP
    rk100

    rk100 Active Member

    Messages:
    539
    Joined:
    Sep 2, 2012
    Car:
    W215 CL65 AMG & W124 E500
    Dash1, again thanks for your latest post.

    Following on from my PM I have carried out the tests you outlined and have outlined the results below.

    Firstly regarding the keyless go one of the keys I have came with the car when I bought it (apparently the others had been lost) and the other one I purchased myself a while back - this key has the more modern chrome around the sides. The key that came with the car does not work with the keyless go so not sure if this is the original or not. Similarly I don't have any receipts which would indicate the module itself was replaced.

    So the first test I did was on Pins 6 and 14 with my multi-meter set on 20M ohms scale and Fuse 83 removed. As noted on my PM I got the following outputs:

    Pin 6 - 2.81
    Pin 14 - 2.82

    As you can see the figures I got is way below the 7M ohms - 9M ohms. I note that you state that these figures are only applicable if the car has the Siemems transceiver. Given the outputs I got maybe I have one of the earlier gateway modules? - not sure either way.

    For the next test I used the blade ammeter in place of Fuse 83 in the order you noted. I got a reading of 0.060 amps. When I used the door to active this i.e. closed the door and waited for the reading to go to zero and then opened the door to active again, it would take ~ 15secs to go to zero. I did this twice with the same results. I also just did this again but used the lights to activate and this time it took ~30secs to go to zero. I did this test again with the same results.

    Even though I never found a constant current being drawn on this circuit I did a global parasitic test with Fuse 83 removed. This give the same results as the previous tests I carried out i.e. 0.04 to 0.11.

    For the next test I removed Fuse 24 and place it in the ammeter in the order noted. When I put the negative lead on the reading when to 0.37 for ~25secs and then dropped to zero. When at zero I switched on the COMMAND unit and left this for 3mins. The reading during this period was 0.78amp for the majority of the time with an odd flux to 0.79amp. When I switched the COMMAND unit off after this it when to zero in 17 secs. I did this test a few times with the readings staying at 0.78amp for the majority of the time with an odd flux to 0.79amp the only difference was the time it took to return to zero. The second time it took 34secs and the third time it took 38secs.

    I did the voltage drop test on Fuse 24 with the multi meter set on the 200m scale. The reading when up to 2.5 when the COMMAND unit was switched on. This went to zero 30secs after the unit was switched off. I did this again and got the same results except this time it took 38secs to return to zero.
    On the final test on Fuse 60 I put the ammeter in place and the reading stayed at 0.27amps until I switched it off. Upon switching off it took 7secs to return to zero. I did this test twice more and the reading remained the same with the exception of the return time to zero which went to 15secs for the second test and 33secs for the third test.

    Hopefully the results above are of some benefit to us.

    Thanks again
     
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  4. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Hi Ray,

    Thanks for the update and the additional information. I’ll cover the points you raise as we go through the post to make it easier to follow. Firstly, the keyless-go issue is a relatively simple “key restore” application process within the module itself if carried out by the dealers using their Star diagnostics if the current car keys can’t be coded in using the conventional “self-learn” procedure. At the end of this post, I’ll post up a step-by-step instruction that you can follow in the event and assuming that the keyless go module has been replaced, however, if it’s the original module (with keys already programmed in) then the “self -learn” procedural sequence would not allow you to enter in to the “key-code” programme anyway, so you will have to try it and see if it works.

    The first tests that you did were on the central gateways transceiver module via pin numbers 6 and 14 and they revealed figures of 2.81M and 2.82M respectively, which as you say in your PM are considerably lower than the ones that I quoted for the Seimens unit. If this was in fact a Seimens transceiver then this really would be an issue for concern, however, we must therefore assume that it is an alternative and possibly one of the others I mentioned earlier, or an even a later generation unit. The only sure way to find this out would be to dismantle the gateway control module and look at the transceiver itself but based upon the other figures you obtained from the same circuit under test then this is not necessary. The circuit does appear to be functioning properly when you substituted the fuse for the in-line ammeter and then recorded a current drain of only 0.060 amps or 60 milliamps, some 20 milliamps less than I stated but my figures were based upon and assuming it to be a Seimens unit.

    In view of these figures Ray, this circuit is functioning properly and I personally don’t see any issues here at all, so all is good. The time out facility is also similar to that I quoted but the main criteria here is the fact that the system did shut down with a current flow reading of zero amps following the end of the test. In any event, when you compared the parasitic drain again, these were still as originally recorded even though Fuse No. 83 had been removed so therefore these modules can’t be contributing to the fluctuating figures and once again just confirms the integrity and functionality of this circuit.

    On the circuit with Fuse No.24, it appears that the current drain was only 0.780 amps, which is again quite low but not uncommon as to warrant any concern, especially with a voltage dropped over the fuse of only 2.5 millivolts. If these two sets of figures are calculated, then a voltage drop of 2.5 millivolts over a 20 amp standard fuse actually represents 0.740 amps, so those figures are not that far away from each other Ray. I note that you didn’t actually remove Fuse No.24 for the final parasitic drain test, it may be advantageous at this stage before we progress for us to do this even though your meter recorded zero amps at the time, the module could still be waking-up and becoming active resulting in fluctuations in the final readings. To rule this out and when you do get the time Ray you can remove Fuse No. 24 prior to doing the final parasitic reading and see if it is contributing to the fluctuations.

    On Fuse No.60 you recorded a current drain of 0.270 amps, again Ray these are very accurate figures and no issues to be worried about here either, I gave you a figure of 0.260 amps and a 0.010 amps differential figure on a circuit with current flowing in it is negligible, especially when you also removed Fuse No.60 from the equation prior to the final parasitic drain test and eliminated this circuit from the fluctuating figures. All in all, the test figures appear to be well within specifications, probably on the lower side more than anything and that is probably down to the fact that these later designed modules are more energy efficient than earlier units, the COMAND unit is a classic example of that so we now need to concentrate on other areas of the car Ray.

    All the tests that we have done to date are non-switched permanent live fused circuits. If you are absolutely happy that the tests are OK, then we can move on to some of the other circuits, possibly the relay circuits now as we don’t need to disconnect the battery here and you can leave your ammeter in series whilst we are doing the tests. As I mentioned earlier on one of my posts, most relay coils consume between 0.150 - 0.175 amps but they could still cause us problems if found to be faulty or malfunctioning as most of these relays anyway are switched on the ground side by the electronic control modules themselves so in this respect it serves two purposes – we can test the relay and module switching functionality.

    Ray, it is equally fair to say here that we can actually measure volt drop lower than 0.001 volts if we want to using your own multimeter by using the other functions under the microvolt scaled divisions. Even when your meter was reading 0.000 volts, there could still be very low current flowing within a circuit and the only true and accurate way to determine this would be to measure the circuits in either milliamps divisions with your in-line circuit ammeter or microamps divisions with your multimeter. Looking at your own multimeter, then it does have several scaled divisions, 10 amps, 200 milliamps, 20 milliamps, 2000 microamps, which is equivalent to 2 milliamps and 200 microamps, which is equivalent to two tenths of 1 milliamp. Very similar scales on the voltage range as well. Most modules these days when in sleep mode consume very little current and are in fact less than 1 milliamps which is something to bear in mind when we are testing circuits. If we need greater accuracy, then we can always use the meters other functions. As I stated in an earlier post Ray, we always start off in the highest range and then scale down for greater accuracy and you will always find it much easier to follow and understand. Anyway, here is the procedure below for the keyless-go key synchronisation.

    Procedure for assignment of keyless-go keys to the keyless-go control module.

    If the keyless go control module is replaced for any reason then the keys/cards for the keyless go control module and the key rails of the electronic ignition/starter switch control module must be reassigned using a new learn-in procedure.

    Procedure: - After replacing the keyless go control module follow the prerequisites as listed below in the sequence as listed.

    Ignition switch in the “OFF” position.

    Do not put the key in the electronic ignition/starter switch control module.

    You must have both of the transmitter cards or keys in vehicle.

    When you are ready, press the keyless go pushbutton start/stop switch in the gear lever and hold it down for approximately 3 seconds until the following message “Visit workshop” appears on the instrument cluster.

    Following the above procedure, the keyless go control module then activates the inductive antenna to recognise the transmitter key/card in the vehicle. When the transmitter key/card is recognised the keyless go control module then initiates the electronic ignition/starter switch control module to switch on circuit 15 via the CAN bus. Following this, it is then necessary to move the selector lever from position "P" to position "R" and then back again. The keyless go control module will then once again initiate the electronic ignition/starter switch control module to “switch off” the ignition via the CAN bus.

    The keyless go control module then searches for the second transmitter key/card. When the second key/card is found the procedure as described above is once again repeated. When the second key/card assignment is also successful the procedure is then completed with the following message “Card in vehicle recognized” being displayed in the instrument cluster.

    If the keys/cards are to be reassigned again after this, it will be necessary to erase the key/card rails in the keyless go control module and this can only be done with the aid of the Star diagnosis equipment.

    Hope this info is of some use Ray and you manage to get the keys coded in, let me know what the outcome is and then we can carry on with the remaining tests. Did you manage to get any test results for the auxiliary fuse/relay circuits that we discussed in the PM? I’m out most of the day tomorrow but will be home later in the evening if you have any questions or concerns.

    Best Regards,

    [FONT=&quot]Dash1[/FONT]
     
  5. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    This post is only following on from a previous personal PM exchange dated 27/08/15 between Ray and myself and with a final update on the latest tests/checks which I outlined for Ray following my last post on the thread. I’ve only included these here now as a matter of interest for anyone that was following the thread and especially with reference to any CL (W215) owners. The principles are exactly one and the same here anyway as with any electrical diagnostics, provided, you can navigate around the chosen circuits of the vehicle you have an issue with. My sincere apologies here but I should have posted it much earlier on but it was included as part of a personal message exchange with Ray.

    Dated: 27/08/2015


    Hi Ray,

    I spent couple of hours reviewing everything earlier this morning that we have done to date so I’ll try and put this in to some form of context. We now know that we have a final parasitic drain at its maximum of 115 milliamps, of which, 0.040 amps is at a fixed value up to the point as and when it starts to fluctuate. If we assume (worst case scenario) that we are looking for the excess of some 75 milliamps at its maximum then we can refine the tests if you wish and try and find it using a lower voltage range than we have currently been using on your multimeter. I’ve put together a fuse chart here, which gives the current drain/voltage drop over every type of fuse rating in the car.

    However, we are going to have to use your multimeter set on the 200 millivolt scale (200m) only. 200 millivolts actually represents a fifth of one volt so its more accurate and its possible we will be able to identify any excess fluctuations within the circuits. As I stated in an earlier post, most modules consume less than 1 milliamp anyway when in sleep mode with the odd exception so we should be able to detect it more accurately using the lower voltage range. As I also mentioned in an earlier post, fluctuating and intermittent current draw at times can prove to be an almost impossible task trying to find it but with patience and determination, even with the most basic tools as a multimeter and ammeter its possible if you go about it in the right way. Here is a list of what we would expect to find with a current drain of 0.075 amps across the relevant named fuses below.

    • 5 amp fuse (Beige) with a 75 milliamp drain is equivalent to a 1.3 millivolt drop or 1300 microvolts.

    • 7.5 amp fuse (Brown) with a 75 milliamp drain is equivalent to a 0.8 millivolt drop or 800 microvolts.

    • 10 amp fuse (Red) with a 75 milliamp drain is equivalent to a 0.6 millivolt drop or 600 microvolts.

    • 15 amp fuse (Blue) with a 75 milliamp drain is equivalent to a 0.4 millivolt drop or 400 microvolts.

    • 20 amp fuse (Yellow) with a 75 milliamp drain is equivalent to a 0.3 millivolt drop or 300 microvolts.

    • 25 amp fuse (White) with a 75 milliamp drain is equivalent to a 0.2 millivolt drop or 200 microvolts.

    • 30 amp fuse (Green) with a 75 milliamp drain is equivalent to a 0.15 millivolt drop or 150 microvolts.

    • 40-amp fuse (Orange) with a 75-milliamp drain is equivalent to a 0.1 millivolt drop or 100 microvolts.
    [FONT=&quot]
    When you checked the “global” parasitic drain readings Ray, when the figures were fluctuating is there a pattern as to how long it does it for, in other words, the frequency in-between. If you can determine this then when you do come to do the volt drop tests then measure the volt drop test over the fuse for a far longer period than you normally would have done to allow for this, the reason I say this is that it may actually be occurring on a circuit that you have either just tested are about to test and you may very well miss it. It’s worth trying at this stage before we move on to the other circuits. If it were me here Ray actually doing this test then I would monitor each volt drop test over every fuse for at least a minute to be sure I haven’t missed anything and it may very well save us time and doing a lot of unnecessary work.

    You don’t have to do them all at once Ray, or even in one day, just concentrate on one fusebox at a time and lets eliminate that part of the system. Effectively, we should be looking to see zero volts on all those circuits if no current is flowing within the circuit. Look at the above chart to give you an idea as to what readings should be obtained given the amount of current flow within the circuit. If you suspect one as fluctuating, then remove that fuse only from the circuit but don’t put it back in until you have finished the tests and then disconnect the battery and replace all the fuses that you have removed, if any.

    We can also now start to identify some of the modules in the event that any of these are causing the issues, we can work on these as “zoned” areas Ray to make it easier and to prevent back-tracking all the time and we can start with the ones which are easily accessible, which are the door and seat modules. The door modules are not directly connected to the seat modules themselves other than by the CAN Bus network and the seat modules only receive commands directly from the door modules with respect to various door module command applications. To save removing the connectors under the seats and disturbing any of the SRS connectors we can isolate them by removing fuse numbers 13, 39, 64 and 66. Remove all these fuses Ray and then measure the global parasitic drain again to see if it’s now diminished with no fluctuations, if it has, then we can now narrow it down to which one is causing the issue.

    Fuse No.13 is the circuit fuse for the n/side door control module.
    Fuse No.64 is the circuit fuse for the n/side seat control adjustment module.
    Fuse No.39 is the circuit fuse for the o/side door control module.
    Fuse No.66 is the circuit fuse for the o/side seat control adjustment module.

    Try the above modules first Ray and lets see what we accomplish from these tests. Let me know what the outcome is.

    Best Regards,

    [/FONT][FONT=&amp]Dash1[/FONT]
     
    Last edited: Sep 19, 2015
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  6. OP
    OP
    rk100

    rk100 Active Member

    Messages:
    539
    Joined:
    Sep 2, 2012
    Car:
    W215 CL65 AMG & W124 E500
    So following on from the post by Dash1 and to keep things up to date on the thread, below is the results I got from these tests.

    I did the voltage drop test over all the fuses with the multi-meter set at the 200 millvolt scale and to my surprise over all the fuses the reading I got was 0.00. I was expecting to get a reading from Fuses 62 and 78 as per the previous time I carried out the test. Just to be certain I did these tests once more on all fuses a couple of hours later and still got 0.00.

    After the above I went about removing the fuses noted:

    · Fuse 13
    · Fuse 64
    · Fuse 39
    · Fuse 66

    I set the car up as per previously outlined with the alarm also activated and measured the global parasitic drain. After an hour I returned and could not believe that the reading was sitting at 0.05 and 0.06 constantly with no higher fluxes. I observed this for at least 30mins. So after seeing this I thought it would be sensible to one by one put the fuses back in (with the negative lead removed) and the readings stayed the same until I replaced Fuse 13 - at this stage the readings varied from 0.05 to 0.012 with this varying every few seconds. Just to be certain I removed Fuse 13 with all the other fuses still in place and left the car - on my return the reading was down to 0.05 to 0.06 and stayed at this. So if I am correct it looks like the fault is on the n/side door control module based on your previous PM indicating what each fuse controls. Maybe I am jumping the gun a bit but I am feeling a little relived that we eventually found something ( I say 'we' because without your assistance I would never have found anything- and to be honest I have learned a massive amount based on all your informative and helpful posts/pm's). Regarding the module is this something that is easily replaced if this is in fact the issue?

    Thanks
    Ray
     
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  7. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Hi Ray,

    Thank you very much for the update, that really is good news now Ray so lets look at what you have covered and I’ll go over the system and what to do next. Disregarding the voltage drop tests for the moment, as these now appear to be stable. The n/side door control module itself is on circuit 30, which is a permanent voltage supply and is via Fuse No.13 - 40 amp orange coloured fuse. As mentioned in my previous post, the door control modules are not directly connected to the seat modules themselves other than by the CAN Bus network and the seat modules only accept command inputs from the door modules based upon what your intended requirements are, i.e., seat forward/back/recline etc. However, directly connected to the door module itself are the following components: -


    • Power window up/down drive motor.
    • Door entrance/exit (puddle) lamp.
    • Door interior exit lever illumination (small lamp behind the chrome lever)
    • Mirror indicator lamp.
    • Exterior mirror combination switch - folding mirror motor - mirror heater - mirror adjustment motors (up/down - in/out) - automatic dimming mirror - mirror fold in/out facility.
    • Front door locking switch.
    • Power door locking pawl.
    • IR - Infrared receiver.
    • OCM - Overhead Control Module – the one in front of the sunroof in the headlining
    • Outside ambient lamp - the lamp under the door mirror itself.
    • Door module illumination.

    So, all in all, there are quite a few components here Ray which are “hard wired” directly to the n/side door control module itself. Lets release the door module first from the door panel and set it up for the next series of tests and we can then disconnect the components on a one-by-one basis and see exactly where the problem is. It may very well be the door module itself here Ray but lets not be too hasty and condemn it until such time as we have proved otherwise. We don’t want to adopt the dealer tactics here Ray for the sake of just changing something and then finding out it wasn’t that fault originally, lets do it properly and how it should be done.

    You can start by disconnecting the battery negative lead first Ray before we start to do anything, then remove Fuse No.13 and place your in-line ammeter in its place and facing you as you can see it as you work on the door module, this way you will be able to monitor the current drain as we remove any module connectors etc. We don’t want the ignition turned on for any of these test either Ray, this is again a single stand-alone test.

    Just above the door module is the ventilated grille, if you get a torch and look inside through the vent you will see a single Phillips headed self-tapping screw. With a longish (6 inch or so) thin bladed screwdriver remove the screw (access it through the second vent up from the bottom) and at the same time hold on to the vent and pull it forward towards you as you are removing the screw, the screw should be held captive in the vent if someone hasn’t already been in there and lost the clip, it will now come away from the door completely. As you now look down on top of the door control module you will see a sliding lever directly on the top, push the lever towards the rear of the car to release both the locking lugs from the door panel, the module will now be released and swing out from the top. At this stage Ray you may wish to get a soft cloth or tea towel and place it under the module to support and prevent it falling out and marking the leather door panel. On the bottom of the module are two locating lugs, to remove the module completely from the door just lift it up and clear of the door panel and pull it forward and let it rest in that position on a soft cloth or so.

    Now re-connect the battery negative lead and observe what the current draw is on Fuse No 13 and make a note of it. The only connector that I do not want you to disconnect at the moment until the very last is the one with the supply voltage in it. It’s a 6-way black coloured male connector plug with a red/black wire, which is the modules voltage supply via Fuse No 13, a thick brown wire, which is the modules ground, the small diameter brown and a brown/red wires are the CAN bus wires and the other two wires which are pink/black and pink/red are the dimmer circuit from the OCM (overhead control module). The rest of the connectors you can remove in any order you wish Ray but make a note of which one you have removed if the ammeter now falls to zero and we can then identify the circuit at fault. You can’t really get the connectors mixed up here Ray, as they will only fit in their respective female cavity anyway, so take care in replacing them afterward to avoid bending any of the pins.

    The other thing to note here is that when you do come to put the door module back in, then make sure the wiring looms are loosely fitted and not overlapping one another if it can be avoided, there is very little room in there to start with and we don’t want to force it back in and break anything. When you are ready and find the time then do all these tests/checks and then let me know if you have found the issue and if not I’ll take you through the final connector plug with the voltage supply, hopefully, you should have found it by now if it’s a component at fault, if not, then we can test the circuit to the overhead control module and the CAN Bus wires.

    Ray, as you already know what my current situation and circumstances are at the moment then I will only be able to get back to you either late Wednesday evening when I finish work or sometime over the next weekend. We are pretty much there now Ray, just a few loose ends to tidy up, if you wish then you can leave Fuse No.13 out of the fusebox until such time as you come to do the tests, (unless you are carrying any passengers and need to adjust the seat) that way it will be less drain on the battery. Also, if we now consider the two readings that you obtained on the final parasitic drain test with Fuse No.13 removed, then these were alternating (I use that word deliberately here Ray as they were not fluctuating) between 0.050 amps and 0.060 amps and on balance we could effectively say that we have a representative stable figure of 0.055 amps, which is not a million miles away from what we are looking for here Ray, the ideal figure was 0.047 amps but that is for the very high specification CL without the additional modules that the CL65 has, also, there could be some inaccuracy within the ammeter which could account for some of it so I wouldn’t worry so much about that.

    The main fact here Ray is that you have actually found the culprit circuit and you have to be commended for the time and dedication that you have put in to doing just that. The CL65 is an extremely complex and an individual car and as I originally pointed out it’s an electrical minefield if you don’t actually know what you are doing and you can do untold damage to the vehicles systems if you are not careful, which is one of the very reasons which I have tried to guide you through with care and caution. I also have to say that I am really impressed with the way you have gone about this Ray and the information you have relayed back. I can only give correct answers based upon accurate information received.

    I’ve also just downloaded a photo from the Internet of a W215 door control module to give you some idea as to what it looks like from the rear view prior to you removing it, also note that they are colour coded cavities to match the connectors, i.e., black, white, blue and yellow, see attached photo below. Let me know how you get on and once again there is no rush to do it, take your time.

    Best Regards,

    [FONT=&quot]Dash1[/FONT]
     
    Last edited: Sep 20, 2015
  8. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Attached photo of W215 door control module.

    Regards,

    Dash1
     

    Attached Files:

  9. kjl

    kjl Active Member

    Messages:
    103
    Joined:
    Jun 26, 2009
    Location:
    Northamptonshire
    Car:
    2014 W212 E350 AMG Sport Bluetec Saloon BMW F800GT Suzuki Burgman 650 Executive
    We haven't heard anything for 2 months now. Is everything sorted. I have been following this thread with interest and would be interested to learn the final end of the story.
     
  10. OP
    OP
    rk100

    rk100 Active Member

    Messages:
    539
    Joined:
    Sep 2, 2012
    Car:
    W215 CL65 AMG & W124 E500
    Hello kjl

    We had it narrowed down to the door control module. Dash1 had provided me with some more additional tests to carry out on top of the ones in the post above (I will post these later just for information) but I have been extremely busy and have not got a chance to really look at this yet - when I do I will give the final update.
     
    2 people like this.
  11. OP
    OP
    rk100

    rk100 Active Member

    Messages:
    539
    Joined:
    Sep 2, 2012
    Car:
    W215 CL65 AMG & W124 E500
    Just an update to the thread - I still have not got chance to carry out all the additional tests - it will be probably next year now!

    As noted in my last email Dash1 had provided me with some more additional tests to carry out on top of the ones in the post above - I have posted these below for information:


    The figures that I am going to quote for these next set of tests are “base line” figures based upon engineering test results with a fixed voltage supply of 13.60 volts, this being the minimum charging voltage that we would allow for. However, I appreciate that you don’t have a fixed voltage supply so we are going to base your figures upon the battery voltage at the start of the test, so please make a note of this first. Some of the tests are going to be done with the ignition switched in the “off” position first and the remainder of the tests are then going to be measured with the ignition switched in the “on” position to make a direct comparison and to allow for any voltage dropped over the circuits and the switched CAN Bus network. I’ll guide you through the process and give you the figures to work with as a guideline and you can give me the exact figures as they appear as you read them on your own multimeter. I can’t form any judgement or opinion at the moment because I don’t know exactly what the battery voltage is on your car until you start to do the test, but it should be in a fully charged state anyway. I’ll do the calculations on your behalf and see if they fall within the parameters of either “pass” or “fail”.

    Just to reassure you, I have no reason whatsoever at this juncture to believe that they will fail, as I have already accounted for some of them anyway in the previous tests on other parts of the network. The whole concept of these tests is to eliminate the sub-sections from the door module itself and if we can do that, then a new door module would be required. As per my previous comment in my last post, it’s very easy for us to just jump to conclusions, but it really is important that we check the system out thoroughly before we even contemplate replacing the module. If there was an issue within the system and you replace the module then we are back to square one again. As there are only 6 wires to look at, I’ll note every wire combination down here so it’s really easy to follow.

    By now you will be familiar with how easy the module comes out of the door panel, so following on from the previous set of tests, then leave all of the other connector plugs in their respective places within the module itself, the battery should now be connected at this stage anyway. The circuits below are for quick reference purposes only and the pin numbering system is1, 3 and 5 on the right hand side of the connector as you look at it once the module is directly facing you when released from the door and pin numbers 2, 4, and 6 on the left hand side as viewed as above.

    • Pin No. 1 is the larger diameter brown wire, which is the modules ground circuit; all the tests will be based from this ground circuit only.
    • Pin No. 2 is the larger red/black wire, which is the modules supply voltage via Fuse No.13.
    • Pin No. 3 is the small diameter brown wire, which is the CAN Bus Low circuit which is directly linked in to the bus network.
    • Pin No. 4 is the small diameter brown/red wire, which is the CAN Bus High circuit which is again linked in to the bus network.
    • Pin No. 5 is the small diameter red/pink wire, which is the dimmer supply voltage input (+) from the overhead control module – (rheostat).
    • Pin No. 6 is the small diameter pink/black wire, which is the dimmer supply voltage input (-) from the overhead control module – (rheostat).
    When ready, put the multimeter black test lead in the back of the connector (back-probe) on pin number 1, which is the brown large diameter ground wire and leave this in this connector for all of the tests, all the tests are measured from this ground point only.

    IGNITION - “OFF”

    Pin number 1 and 2 should be…13.57 volts - Voltage supply to the control module.
    Pin number 1 and 3 should be…12.70 volts - CAN Bus “Low” - inactive and on standby.
    Pin number 1 and 4 should be…00.50 volts - CAN Bus “High” - inactive and on standby.
    Pin number 1 and 5 should be…00.00 volts - Dimmer (rheostat) - system switched off.
    Pin number 1 and 6 should be…13.57 volts - Dimmer (rheostat) - system switched off.

    IGNITION - “ON”

    Pin number 1 and 2 should be…12.57 volts - Voltage supply to the control module.
    Pin number 1 and 3 should be… 4.30 volts - CAN Bus “Low” - active and switched on.
    Pin number 1 and 4 should be…00.70 volts - CAN Bus “High” - active and switched on.
    Pin number 1 and 5 should be… 1.20 volts - Dimmer (rheostat) - system switched on.
    Pin number 1 and 6 should be…12.57 volts - Dimmer (rheostat) - system switched on.

    Don’t worry if your readings don’t match the above, just keep in mind that when you switch the ignition on then all electrical loads within the car will automatically become active and the battery voltage will start to drop away anyway, all I’m looking for here is any strange behaviour or abnormalities. Carry out the above tests and let me know what the results are. There are some visual tests/checks anyway that you can also do to confirm that the components are working directly from the door module, such as the dimmer circuit, seat movement travel etc. anything you can possibly use from the door module then see if they actually work.

    Let me know how you get on and I’ll speak to you sometime at the weekend, probably late on Sunday afternoon now.

    The only thing that I forgot to mention in my last post is when you do come to do the tests, then leave the black 6-pin plug (the one with the power supply in it) connected in to the module itself and don’t remove it, also, leave all of the other connectors in place during these tests. When you come to do the tests, then place your multimeter black test lead in the brown wire (pin number 1 socket) at the rear of the plug (back-probe) and with your other multimeters red lead just back-probe in to the rear of the other wires and read off the values on your multimeter.
     
  12. Roadtoad

    Roadtoad New Member

    Messages:
    2
    Joined:
    Dec 23, 2012
    Car:
    Mercedes W215 YR 2000
    Hi all Ive not posted on here before but I have been a visitor for quite some time. This thread in particular has been a great source of information as I too have had a battery drain on my pre face lift W215. The main difference being that my car does not have the fuses at the side of the dashboard. So to cut a long story short I have found that my battery drain was caused by a faulty alarm which I have now removed. It was hard to trace because I couldnt find a fuse that the drain went through. As soon as I removed the alarm however the drain stopped and my simple test bulb light attached between the neg battery terminal and the ground wire which had always shone brightly, went out. But during my efforts to find the drain, one of the things I did was to disconnect the battery and left it overnight. The reason being that I got fed up of putting the battery on charge each day between my fault finding endeavours. This may have introduced the fault which I now have, namely the SRS warning light wont go out. I have a star machine but even with this I cannot remove the fault. I also have other niggly things cropping up like the fact that star now asks me for the mileage each time I connect. Also it shows a problem with the ICM - instrument cluster module, but when I try to analyse the problem I cant get into it. The SRS Airbag problem looks like being the fault of module n2/7 the airbag control module. It is situated under the front of the centre console but before I start removing the console to get to it I thought I would see if there are any pearls of wisdom on here as to why I have suddenly developed these problems and if indeed it is as I suspect a problem of my own making in my leaving the battery off over night or is it perhaps the fact I have now removed the alarm. I see no connection between the alarm and the SRS but as these cars are like voodoo on four wheels I thought I had better ask. I have uploaded screen shots of my star to try to show what Im on about. Dash1 can you help ?
    1st picture showing star asking for mileage each time
    [​IMG]
    2nd picture showing ICM anomoly
    [​IMG]
    3rd picture shows message you get when trying to access the ICM
    [​IMG]
    4th picture showing airbag fault code reasons
    [​IMG]
    5th picture shows star fault finding procedure
    [​IMG]
    Final picture shows star asking for value when module n2/7 is unplugged
    (not yet done)
    [​IMG]
     
  13. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Hello Roadtoad,

    Thank you for the questions although you have significantly deviated from the original aim of the thread. The code/designation number for the circuit that you refer to here in the screen shot photos - A1e15 is the SRS - MIL (supplementary restraints system - malfunction indicator lamp), which is “hard wired” directly from the restraints control module itself (pink wire) to the instrument cluster. It has to be wired in this configuration and not networked over the CAN Bus for two very specific reasons, one being that it is a “tell-tale” warning indication that some component within the system has malfunctioned and secondly its an observational icon from a self-diagnostic test point of view, i.e., it should illuminate with the ignition switched in the “On” position of between 4 and up to 20 seconds as indicated in the frame and then go out if the systems self-diagnostic checks are within specification, if not, then the lamp will remain illuminated until such time as you retrieve and read the fault codes, identify any issues and then erase them once repaired.

    If it’s a “hard fault” then it will remain on, however, if it’s an historic or pending code then these can be removed successfully with any suitable code reader/eraser. This “safety critical” information is not suitable for transmission purposes on a data bus network and has to be under the direct control of the SRS module itself. This system really is complex but the module itself does also rely upon other safety critical information and data from other parts of the car, examples being the seat control module in the event of driver airbag deployment – first/second stage process, roof and door control modules to establish the open/close positions of the sunroof and side window glass.

    The designation/identification code - “A1” is the instrument cluster itself and the remainder of the code - “e15” is the identity of the circuit that is “allegedly” at fault. The additional code, B1476 is a generic OBD II body code anyway which is specific and related to the circuit from the restraints control module to the instrument cluster, therefore, the two are directly related and linked. There is also something else which you failed to mention here which I also noted from your screen shot photos, there is additional information, which supports the fact that there is another more important key aspect here, which supports and represents the fault code (1.3)-3.515.2005. This is a communicational error code, and its not just specific to any Mercedes Benz anyway, its found on all European car manufactures vehicles which means that communication has not been established with the instrument cluster and the diagnostic test equipment through the OBD II connector plug - J1962, and hence the error frame as pictured and identified in your photo screen shot number 3.

    The reason that you have to keep entering the mileage in Star is because Star is unable to communicate with the cluster to retrieve the current mileage data. I think you will find, that it is extremely plausible here in your case is that if you check all the connections (bent/dirty pins etc) from your laptop to the multiplexer interface module (MUX) and from the multiplexer to the diagnostic port J1962 on the car you may very well find the issue, it could very well be a bad connection behind the instrument cluster itself. The connector pin number on a Mercedes Benz vehicle in the diagnostic connector block - J1962 under the dash is pin number 15 (white/blue wire) and is directly connected and linked in to the instrument cluster itself for communication purposes only – check all your connections here. You may very well be asking yourself the question then why is Star communicating with the other modules on the car, the simple answer to this is that this circuit is a “stand alone” bi-directional circuit and information is transmitted to the cluster from Star and information is also accessed via Star. In addition to that, this particular circuit is also spliced, supports and shares its diagnostic link with the distronic control and the xenon headlamp control modules if indeed you have these fitted to your car - optional equipment. Try all these areas first before you even consider any faults on the car.

    There are several other reasons anyway in the event the above does not rectify your issues, which you will have to visually check, examples of these are the fuses etc. You are absolutely correct when you say that your car does not have the fusebox at the side of the dash, they are actually located in the n/side front fusebox on the earlier CL’s. Check these fuses first – fuse numbers 20, 21 and 22, these are all 7.5 amp brown fuses found in the n/side front fusebox. You can also check the ignition switched voltage supply to the restraints control module itself as this is directly powered up from the EIS (electronic ignition switch – pink/red wire which changes colour (spliced) to a pink/green wire at the srs module).

    I also noted from the screen shots that you provided that there is an issue with a seat and a door module, don’t lose sight of the fact here that if any of these modules are defective or malfunctioning then the SRS system is directly linked to the seat module (first and second stage occupancy deployment sensors being an example). Have you ever disconnected any of these connectors with the ignition switched in the “On” position – check all the connections and wiring under the seat and the harness from the cabin to the doors as the CL’s have known issues here relating to the wiring harness breaking in these areas. It’s a lot to take in but I really don’t have the time anymore to get involved in forum activities or guide you through this and this will probably be my last post on the forum for a good while anyway. I only came on here today to leave Ray (rk100) a message and noticed that you had posted a question on the thread, so out of courtesy I have answered it as best as I can in the circumstances. I haven’t posted on this thread for some 3 months now, as I don’t frequent the forum that often anyway.

    The answer to the other questions you asked, then leaving the vehicles battery disconnected overnight will have no effect whatsoever or contribute to any of the symptoms/faults that you may have, unless, you have inadvertently disturbed any of the SRS connectors and then switched the ignition on. Also, disconnecting the alarm system or removing it plays no part whatsoever in the symptoms you described – they are entirely different circuits and not linked in any way

    I don’t know anything about the voodoo electric theory you refer to, but every issue/symptom has to have an explanation and a suitable answer. What I can say with absolute clarity and authority though is that these cars are extremely complex and should not be tampered with unless you really do know what you are doing. Don’t initially condemn any modules, especially the SRS module, until you are absolutely sure its not a sub-system component that it at fault. Don’t mind me asking, but are you a mechanic or auto-electrician by profession anyway?

    Hope all this info helps and my very best wishes for Christmas and the New Year, good luck with the car.

    Best Regards,

    [FONT=&quot]Dash1[/FONT]
     
  14. Dash1

    Dash1 Active Member

    Messages:
    228
    Joined:
    Nov 9, 2010
    Location:
    Merseyside/Staffordshire
    Car:
    2013-Audi A8L (W12) Exclusive (D4) 1998 H-D FLHTCUi and FLSTS 95th Anniversary Models.
    Hello Roadtoad,

    I’m not sure whether or not you have read my earlier post yet but I also meant to ask you a question regarding the multifunctional display in the centre of the instrument cluster when you turned on the ignition. If a “hard fault” should exist anywhere within the supplementary restraints control system, then this would have shown up and been highlighted with the following error message - "RESTRAINT SYSTEM, VISIT WORKSHOP",which would have been red in colour, as I have indicated here.

    The instrument cluster doesn’t give any specifics relating to any one particular fault from the SRS system, its not designed to do that, it just reads in a single message which allows the instrument cluster to display the above message (in red) and you are then supposed to take the vehicle in to the dealers and have the SRS module interrogated for any relevant fault codes. Did you actually notice if this warning message was present as the malfunction message displayed in the instrument cluster would have been sent over the CAN Bus network from the SRS module. Checks if this warning message is present the next time you turn the ignition on, especially if a fault is known to exist.

    If such a warning message was not shown then the instrument cluster will not have been in communication with the SRS module, therefore, in serious communicational instances such as this, the instrument cluster would have detected this failure and independently actuated the SRS - MIL warning lamp automatically, therefore alerting the driver that an issue exists. The instrument cluster has priority here (protocol) over any communicational errors with the SRS system and stores the relevant code and data in its memory. Its very complex, but you really do need to know and understand how these systems are integrated and function, so I’ll try and simplify it as best I can below.

    To try and simplify this as much as possible, then think of it this way, we know that the SRS module is giving you the error codes - A1-e15 and B1476, this is because it has monitored that the SRS warning lamp is still on after its initial cyclic (4 to 20 second time frame) diagnostic self-check with the ignition turned on, therefore, its set the trouble code, however, because of the lack of communication between the instrument cluster and the SRS module over the CAN Bus, the instrument cluster has actuated the MIL lamp automatically as it is designed and supposed to do this anyway in an emergency situation such as this.

    If you also look at it from an alternative point of view, then it becomes much clearer and easier to understand. If the instrument cluster is unable to display any malfunction warning messages from the SRS system because of a communicational error between the two modules, then how is it supposed to let the driver know that a fault issue may exist. By design, the only “fail-safe” way of the instrument cluster doing this is by illuminating the SRS - MIL lamp through its own internal circuitry, otherwise, the driver could very well be driving around being non-the-wiser that the SRS system has been disabled as a result of a fault. When the SRS - MIL lamp is on, then the whole of the SRS system is disabled and the only elemental form of safety protection here in the event of an accident/collision scenario is the three point seat belt protection, there is no intervention or safety element provided whatsoever here from the SRS system.

    Your own diagnostic equipment has highlighted this communicational error in screen shot photo number 3, as you yourself stated that you were unable to communicate with the instrument cluster, which was one of the questions that you asked about. Also, it would appear that you were unable to delete the fault code and turn off the MIL lamp either; the reason being is that the lamp was under the direct control of the instrument cluster itself and not the SRS module. The SRS module has no control whatsoever over the MIL lamp whilst it’s still unable to communicate with the instrument cluster. I think you will see as and when you do get access to the instrument cluster, then you will find the relevant communication fault codes stored in there anyway.

    At the moment, assuming there is no warning message in the instrument cluster, then I wouldn’t waste my time looking for something that may not even be there, concentrate your efforts here first on getting the cluster back up in to normal service as I outlined in my previous post above, check all the three fuses, 20, 21 and 22 and then read all the fault codes. Given your descriptions anyway of the symptoms and the data that you have provided, your problem here appears to be with the instrument cluster itself that has put the SRS lamp on because of a communicational error with the SRS module over the data bus, as soon as this is rectified, the sooner the SRS system will revert back to its normal diagnostic self-test sequence.

    You asked me a direct question at the latter end of your post if I could help, I’ve given you two differing scenarios here to work with, which one applies in your case depends entirely upon whether or not you have seen the malfunction message - "RESTRAINT SYSTEM, VISIT WORKSHOP" displayed in the instrument cluster window. As you have already stated, your Star equipment is unable to communicate with the instrument cluster because you have to keep entering the vehicles mileage in manually, get the instrument cluster up and communicating with Star first and then work from here.

    Hope this additional information helps, take care and best wishes once again for Christmas and the New Year.

    Best Regards,

    [FONT=&quot]Dash1[/FONT]
     
    Last edited: Dec 24, 2015
  15. Roadtoad

    Roadtoad New Member

    Messages:
    2
    Joined:
    Dec 23, 2012
    Car:
    Mercedes W215 YR 2000
    Thank You very much for your response Dash1. I understand you dont have much time to visit the forum. The good news is I have now found what the problem was after using your advice to first check the fuses. I didnt have the red "Visit Workshop" warning, only the SRS light was on so your advice to first check fuses 20,21,22 was spot on. I had made a real "rookie" error in my efforts to find the battery drain problem. I was using a fuse blade connector multimeter where you pull the fuse out and insert it in the side of the device before sticking the probes into the fuse holder. It looks like I had left fuse 21 in the device and not replaced it after testing it and this was throwing the Instrument cluster out and of course illuminating the SRS light. This on the face of it seems like a really stupid thing to do but I remember now that on that particular day I had to hurry up my efforts due to the onset of rain to get the bonnet shut before everything got wet and in doing so left the fuse in the tester. After replacing the fuse and running SDS to cancel out the stored error message the car now has a clean bill of health and shows no error messages at all. A happy new year to you and once again Thank You
     

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