Battery Discharging CL55

[John Moors]

Annoying problem to have but I understand 'not unusual' for 03-05 CL's.
Basically battery discharges without using my CL55 for say four / five days. Battery new and alternator checked and good. Computer check reveals no faults at main dealer. So something is draining it!
Done usual checks -
1/ Boot lights go out on electric close
2/ Dashboard glovebox goes out when closed
3/ Central console glovebox doesn't go out!
4/ Rear nearside window switch is unlit and won't operate the window, although the switch on the drivers door does.

So which is the most likely cause??
a)I believe the glovebox light is known to be problematic although I fail to see how a small orange diode light can drain a battery in three - four days.
b) Likelihood of a loose connection and short on the rear nearside window switch? How do you dismantle the switch etc?
Any help / advise would be appreciated as I won't sell the car - it's immaculate with low mileage....

Does the CL have an additional battery for starting the engine similar to the earlier SL's??
John

 

[Dash1]

Annoying problem to have but I understand 'not unusual' for 03-05 CL's.
Basically battery discharges without using my CL55 for say four / five days. Battery new and alternator checked and good. Computer check reveals no faults at main dealer. So something is draining it!
Done usual checks -
1/ Boot lights go out on electric close
2/ Dashboard glovebox goes out when closed
3/ Central console glovebox doesn't go out!
4/ Rear nearside window switch is unlit and won't operate the window, although the switch on the drivers door does.

So which is the most likely cause??
a)I believe the glovebox light is known to be problematic although I fail to see how a small orange diode light can drain a battery in three - four days.
b) Likelihood of a loose connection and short on the rear nearside window switch? How do you dismantle the switch etc?
Any help / advise would be appreciated as I won't sell the car - it's immaculate with low mileage....

Does the CL have an additional battery for starting the engine similar to the earlier SL's??
John

Hello John,

Firstly, lets try and give you some specific and sound advice on how to go about diagnosing this electrical problem, if indeed it is a problem.

Secondly, I have to ask this question at this point, have you got any electrical experience or knowledge whatsoever within the autmotive industry, and there is a very good reason that I am asking this question. The series of test that I am about to relay to you would require you to have sufficient skills in the use and operation of using a digital multimeter - ohms/volts/amps.

Come back to me with your answer, and then we can begin.

Best Regards,

Dash1

 

[Dash1]

Dash1

 

[John Moors]

Dash, Yes I can use a multi-meter. Have re-wired houses previously and know my way ound a car.
J

 

[C43AMG]

Hello John,

Firstly, lets try and give you some specific and sound advice on how to go about diagnosing this electrical problem, if indeed it is a problem.

Secondly, I have to ask this question at this point, have you got any electrical experience or knowledge whatsoever within the autmotive industry, and there is a very good reason that I am asking this question. The series of test that I am about to relay to you would require you to have sufficient skills in the use and operation of using a digital multimeter - ohms/volts/amps.

Come back to me with your answer, and then we can begin.

Best Regards,

Dash1

Like being back at school

 

[John Moors]

Dash,
Its beginning to feel that way already.
To be clear I have little experience in diagnosing this type of problem in a car.
Houses are a lot simpler!
What do you suggest?
J

 

[Dash1]

Dash,
Its beginning to feel that way already.
To be clear I have little experience in diagnosing this type of problem in a car.
Houses are a lot simpler!
What do you suggest?
J

Hello again John,

My apologies for the delay in getting back to you, I do work extremely long hours and sometimes it’s quite difficult to come on the MB site. I came on earlier today to see if you had replied, but I did not have enough time to respond. I am in fact a mechanical/electrical engineer with the Jaguar/Land Rover Group and to say there is not enough hours in a day would be an understatement.

And yes, in answer to C43AMG’s comment, it is sometimes like being back at school, especially when you are trying to guide someone through a complex process and not being there in person to help. Unfortunately, this is the only method of approach to adopt when someone knows little about a subject, as you have honestly admitted.

Firstly, do you have a paper copy of the fusebox layout for your vehicle, if not, then you will have to PM me your email address and I will supply you with a copy of my own version, far better than any Mercedes Benz schematics.

Secondly, we need to identify what you actually have fitted to the vehicle to ascertain the maximum current drain from the system when it’s in "sleep" mode. By this, I mean when the vehicle is locked and secured, all modules are shut down and the immobiliser/alarm is active and live. In addition to this, we need to know what may in fact be causing the problem. It may very well be one of the components from your optional equipment list, so this is very important.

I will use my own CL500 as an example so as to give you some idea as to what electrical values you should expect to find from your vehicle. The topology and electrical architecture of my vehicle is pretty much identical in every way to that of your CL55. My vehicle, at the moment, is in perfect electrical order, so I know the values I obtained are correct and accurate.

My own vehicle is fully loaded with every single option that was available at the time of manufacture, in fact, its now six years old and when I bought it five years ago and looked at the options list from the brochure, the only option not chosen was in fact the TPMS (Tyre Pressure Monitoring System) everything else is fitted. Mercedes Benz tell me that its the highest specification CL500 in the UK, which was in fact borne out by the £97,400.00 price tag and what the gentleman and original owner told me whom I bought it from.

I have just recently changed my own battery on 10/01/2011 from its original Varta 95Ah to a Bosch S5 100Ah. At the time of fitting the battery, I measured the quiescent/parasitic drain to establish if I may have had a fault, thankfully I haven’t. But I have had some major electrical issues with this car over the past five years.

You may very well know this, but for information purposes, quiescent/parasitic drain is a term used to express the "maximum" current drain from any system on its power source when the vehicle is in "sleep" mode. Every vehicle manufacturer has differing threshold levels, some greater than others. The maximum drain I’ve identified on my system was in fact 0.036 amps or 36mA. So this figure is what you should be looking for. As I mentioned earlier, I am a mechanical and electrical engineer for Jaguar/Land Rover Cars and even our flagship models, Jaguar XJ (351) and the Range Rover (L322) only have a quiescent drain of approx 50mA.

There are very many trains of thought on the process of going about testing and evaluating this data, we will look at them, but for now, lets see if you have sufficient cause for concern.

The first test that I want you to do would be a "dead" test, by this, I actually mean the system must be completely isolated from any power source whatsoever and all capacitors drained down. When you disconnect the battery, many of the modules, especially the SRS (Supplementary Restraints System) will still retain power sufficient to deploy the airbags in the event of a frontal or side impact occurring and the battery/power source being disconnected from the system. This has to be so for safety reasons and is specified by the SAE.

When you disconnect your battery and remove both the positive and negative leads, the alarm will go off and you must let it stop on its own. Once it has stopped, connect both the battery leads together for approx 30 seconds, all capacitors should drain by this method leaving the system in its "dead" state. Alternatively, just leave the battery disconnected for approx one hour

The first test to do would be to establish if you actually now have a "live" short to ground issue on your system. If you have a digital multimeter, then you must select the ohms range and then place the meters leads together, you should obtain a reading of approx 0.001/0.002 or thereabouts, depending on the quality of the equipment your using. This value must be deducted from any reading you obtain from the vehicles system to accurately assess the true data value.

Now switch the meter on and with the leads of the multimeter connect them to both the positive and negative battery terminal leads on the vehicle, the meter reading value from my vehicle under these test conditions was in fact 121 ohms, yours should be something similar as the electrical architecture and topology are one and the same. If you obtain a reading similar to that of the reading obtained from the meter leads connected together alone, i.e., 0.001/0.002, then for sure you have a short to ground issue and one of the components and/or wiring loom is making contact with the earth/ground circuit.

For now though, lets just go about this basic task and we will progress further if need be. Dependant upon the results that you obtain from your vehicle, then there are very many different electrical diagnostic routes that we can take. One step at a time though, and yes, it will seem like you are back at school. But what was wrong with school anyway.

Regards,

Dash1

 

[John Moors]

Pete,
This is going to take a while isn't it.....
Lets start with today's activity - replaced battery (Varta 100amp silver) with a piece of ****e 95 ohm box which means I can use the vehicle. Have taken out the CD disc unit and Sat Nav disc in case their spinning when the vehicle locked etc, I'll see if this shows any improvement.
On Sunday I'll put the multi-meter on and do as you suggest, if there's a drain I'll note the value etc and mail you - I'm contactable on john.moors [email protected]
Car specs could be interesting -
I've got everything including tyre pressure monitors, oh no told a lie, no distronic (wasn't available on a 53 plate). Telly working on digital conversion, phone, boot close, bi-xenon, pulse heated / cooled seats, 19ins corners, paddle box. Pretty standard CL55K in Obsidian Black and charcoal, but it is a 'black' edition with a claimed 564 bhp. Not quite 'the class' of your colour and interior (am sure I've seen the vehicle, I chased one very similar in in Wilmslow Sep last year but the asking price of £23k was a bit rich, got pipped at the post by someone down south)

Anyways, I'll run the dead test as you suggest. with CD's in and then out - you never know!!
Thanks for your advice, need to get this sorted before I run it to stage 2, uprated Kompressor pulleys and bigger belt plus induction conversion (want to take the torque and bhp to within 10% of the max rating for the box, te he).....
J

 

[Dash1]

Pete,
This is going to take a while isn't it.....
Lets start with today's activity - replaced battery (Varta 100amp silver) with a piece of ****e 95 ohm box which means I can use the vehicle. Have taken out the CD disc unit and Sat Nav disc in case their spinning when the vehicle locked etc, I'll see if this shows any improvement.
On Sunday I'll put the multi-meter on and do as you suggest, if there's a drain I'll note the value etc and mail you - I'm contactable on john.moors [email protected]
Car specs could be interesting -
I've got everything including tyre pressure monitors, oh no told a lie, no distronic (wasn't available on a 53 plate). Telly working on digital conversion, phone, boot close, bi-xenon, pulse heated / cooled seats, 19ins corners, paddle box. Pretty standard CL55K in Obsidian Black and charcoal, but it is a 'black' edition with 564 bhp. Not quite 'the class' of your colour and interior (am sure I've seen the vehicle, reckon I chased buying it in Wilmslow Sep last year but got pipped at the post maybe)

Anyways, I'll run the dead test as you suggest. with CD's in and then out - you never know!!
Thanks for your advice, need to get this sorted before I run it to stage 2, uprated Kompressor pulleys and bigger belt plus induction conversion (want to take the torque and bhp to within 10% of the max rating for the box, te he).....
J

Hello John,

Firstly, my name is not Pete as you have implied. You must have mistaken me for someone else and in the process commented upon some of my suggestions in my post reply.

Whats going on?

Secondly, my vehicle has never been up for sale in Wilmslow, or anywhere else come to that matter, so how on earth have you managed to just miss out on buying it. How can you compare my vehicle to your own vehicle when you have never ever seen my vehicle.

I am genuinely trying to give you help and advice here and you can't even communicate with the right person. It looks to me that you already have someone by the name of Pete already giving you guidance, so I'll be signing off.

Regards,

Dash1

 

[jeffwebb]

That went well
I thought we were going to get some really useful electrical advice,possibly even a sticky, and then it all went udders up. Oh well.

 

[John Moors]

Udders up it does in fact seem.............

 

[trainer]

I thought this was a forum where there were quite a number of people with given expertise who pooled their resources to help another member achieve a result. I know nothing about car electrics but a number of people helped me solve my battery drain problem.

John, my car is very different from yours but my battery drain fault was down to the passenger memory seat controller. The 'constant' feed was causing a battery drain. I was pointed in the right direction by several members and paid for a full check by MB. It cost £100 but saved me doing some damage.

Disconnecting the constant feed and limiting it to only work when the key is in saved the day. The passenger memory controls work as they should but only when the key is in.

I hope you find your problem, I am sure more help will be on its' way.

 

[alibally]

Someones in the huff then. But seriously its best to get an auto spark or a dealer to check it out if your not sure. It will save you time in the long run.

 

[John Moors]

All,
Thanks for help and assistance (or otherwise).
Fault diagnosed via a multi-meter test as suggested by Dash originally (belated thanks).
First test showed a drain of 0.3-0.4 amps (multimeter showed a self-test reading of just under 0.2amps). So at first analysis it suggests 'no drain' which is what the main dealer reported.
However when locked in a silent garage the vehicle started making noises in the boot and the multi-meter showed a drain of 5.8amps..... Source was the CD changer periodically re-loading all the CD's then continuing to 'spin' the discs indefinitely reducing the drain to 3.5amps.....
Hence the extended discharge period!
Cheap cure - remove the 6CD cartridge from the changer unit after use until a full replacement unit can be sourced. Works but not exactly convenient.
Anyone ever found a suitable repairer for the changer unit or a possible cause for the fault - wrong CD cartridge possibly??

 

[Dash1]

Hello John,

I'm glad to hear that you have now sorted the problem out and resolved the issue.

And yes, my CD changer has also been replaced, fortunately though, mine was under warranty at the time as the vehicle was only 14 months old.

Believe it or not, I had to tell the MB technicians what the fault was as they also could not find any issue after leaving the vehicle with them for three days. No STAR machine served them people very well, they probably didn't even know how to use it correctly.

Very poor service indeed from a main dealer, I've never been back there since. I've lost complete confidence in their ability to solve and rectify issues. I do use an alternative MB main dealer just to do the servicing requirements only now, and this is primarily to keep the service records up to date and for any future paint/warranty issues.

Anyway, as a gesture of goodwill, I have emailed you my own version of the MB fusebox arrangement and layout for the (W215) model CL's. I hope it is of use to you, If my vehicle was anything to go by, then you may need it in the future

Print it off and keep it in the vehicle for future reference purposes.

Regards,

Dash1

 

[Dash1]

Hello again John,

Just to confirm and satisfy yourself that you are happy that you have indeed isolated the excess current/parasitic drain to the CD changer unit. Then there is an even easier way now that we can indeed confirm this.

Follow this procedure, which is an even easier way than the first one.

The circuit responsible for the CD changer unit is controlled through fuse 23, which is in fact a 7.5 amp brown fuse and is located in the n/side fusebox in the engine compartment. (5th fuse up from the bottom left hand side corner of the fusebox)

You do not need to do anything really technical here, with the ignition switch turned to the "off" position, remove fuse 23 and insert your ammeter now in place of the fuse.

Now turn your ignition switch back on and monitor the circuit, it should reveal the data that you originally posted as being in excess of some 5 amps draw.

Now turn the ignition switch back off and once again monitor the circuit to confirm that it is actually drawing zero amps after shutdown.

Monitor this procedure over the next 30 minutes or so without actually touching the vehicle.

Regards,

Dash1

 

[John Moors]

Final Outcome - faulty CD changer caused by water ingress / damp. Replacement on exchange £500 or a guaranteed fix for min £120 plus labour at the hour. Trying to trace a recon replacement etc.
Thanks to all.
JM :bannana:

 

[pietro67]

Hello John,

Firstly, lets try and give you some specific and sound advice on how to go about diagnosing this electrical problem, if indeed it is a problem.

Secondly, I have to ask this question at this point, have you got any electrical experience or knowledge whatsoever within the autmotive industry, and there is a very good reason that I am asking this question. The series of test that I am about to relay to you would require you to have sufficient skills in the use and operation of using a digital multimeter - ohms/volts/amps.

Come back to me with your answer, and then we can begin.

Best Regards,

Dash1

hello dash been reading your discussion on battery drain and would very much like to read your further instructions as due to disagreement with the fella you were discussing what to do youdidnt complete your recommendations on things to do further more would very much appreciate copy of improved version of fuse diagrams my car is a 2001 cl55amg with all extras not sure if has tyre pressure mode though .Anyway would be very great full for your imput on battery drain as I have this problem but mine dies around 24hrs but not completely but left longer then goes completely flat kind regards Pete

 

[bob6600]

hello dash been reading your discussion on battery drain and would very much like to read your further instructions as due to disagreement with the fella you were discussing what to do youdidnt complete your recommendations on things to do further more would very much appreciate copy of improved version of fuse diagrams my car is a 2001 cl55amg with all extras not sure if has tyre pressure mode though .Anyway would be very great full for your imput on battery drain as I have this problem but mine dies around 24hrs but not completely but left longer then goes completely flat kind regards Pete

Dash1 hasn't been active for nearly 5 years