2008 W221 S320 CDI - Proper way to change rear (consumer) battery and should it be a AGM or Non-AGM?

[geoffus]

I'm lost now, is it your starter battery you are having trouble with or your consumer battery ?
If its your starter battery the just buy the AGM version it will work better for the stop/start function,
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[Diesel Benz]

I'm lost now, is it your starter battery you are having trouble with or your consumer battery ?
If its your starter battery the just buy the AGM version it will work better for the stop/start function,
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I'd promote AGM but not for stop/star, a 2008 221 should not have that?

 

[geoffus]

I'd promote AGM but not for stop/star, a 2008 221 should not have that?

Although maybe not fitted originally its a worthy upgrade, an AGM will perform better with stop/start and the price is marginal now.

 

[Diesel Benz]

Although maybe not fitted originally its a worthy upgrade, an AGM will perform better with stop/start and the price is marginal now.

I believe the original battery is an AGM battery. If it was not, I'd be a bit concerned about the different charging voltages for the two. AGM battery would accept the charging voltage for a normal battery but might not get fully charged. Perhaps still behaves better, specifically at cold weather where it is most important.

 

[mbenz1]

Apologies all as I haven't set up notifications on my phone for this app. Will do soon.

Its the consumer battery (located in the rear boot) that's low on charge.

I believe the original battery is an AGM battery. If it was not, I'd be a bit concerned about the different charging voltages for the two. AGM battery would accept the charging voltage for a normal battery but might not get fully charged. Perhaps still behaves better, specifically at cold weather where it is most important.

You mention 'the original battery is a AGM'... are you referring to the starter battery or the consumer battery? The rear battery (original MB battery) mentions 'VRLA' on it but not sure if its a AGM VRLA or non-AGM VRLA...

We replaced the starter battery in 2019 with a specific Bosch unit from ECP (ECP recommended the correct battery according to their database) and it is not a AGM battery... Is this something of a concern - i.e. should both front and rear batteries be of the same type? The rear battery says VRLA on it (original MB battery) so should the front also be VRLA?

Back to the main problem, if you look back to my 1st post regarding the yellow engine fan light and engine fan on when car is cold started - we have been using the car over the last couple of weeks now and noticed that once the car is started, the fan stays on until the engine is warmed up - once engine reaches 90C, fan goes off and never comes on again. I have read elsewhere that there is a sensor in the screen wash reservoir and the coolant expansion tank, which are both connected in series. If one sensor fails, it can trigger this engine fan light etc.

I would like to know for the W221 Pre-facelift 2008 model:

1) Is there actually a sensor in the coolant tank? (I was told there isn't but wanted to confirm this). If there is, what could the part number be (assuming it is a replaceable part)?
2) Part number for the sensor in the screen wash reservoir (again, assuming it is a replaceable part)
3) Part number for the engine fan unit - my local MB specialist told me it is A2219066500 but this appears to be for the facelift models when I search it in eBay.

Star Diagnosis says: 1636-004 - Check component M4/7 engine fan - discontinuity of signal line.

I am told it most likely could be the fan unit but would like to try the sensor(s) first before spending £££ on a new/used fan unit.

Thanks.

 

[Diesel Benz]

There is a sensor in the coolant reservoir, you should see the wires to the tank. EPC did not show a sensor as a separate part, at least not on the page where the tank is. No big surprise if it appears on an odd page.

Screen washer sensor is likely A2218209110.

The fan unit should be searched with the vehicle VIN.

Why interested on the washer sensor? Surely cannot affect the fan?

 

[mbenz1]

There is a sensor in the coolant reservoir, you should see the wires to the tank. EPC did not show a sensor as a separate part, at least not on the page where the tank is. No big surprise if it appears on an odd page.

Screen washer sensor is likely A2218209110.

The fan unit should be searched with the vehicle VIN.

Why interested on the washer sensor? Surely cannot affect the fan?

The VIN is WDD2210222A190558 - sorry as I forgot to re-mention it from the last page.

I read a thread on another forum about a W221 S350 petrol where someone mentioned it has the coolant and screen wash (temperature?) sensor wired in series and if one of the two sensors go bad, it can trigger a engine fan light ON and engine fan ON situation because the fan thinks the coolant temperature is too high or because it is detecting a faulty sensor and puts the fan on as a precautionary measure. If this is true, it surely must be wiser to replace both sensors and then see if the problem comes back - if it does then that can only mean one thing, the engine fan.

As mentioned, STAR is saying 1636-004 - Check component M4/7 engine fan - discontinuity of signal line. I take it discontinuity of signal line means no feed from a sensor right? If I am correct, it could mean there is a faulty sensor that is causing this symptom.

Thanks.

 

[Diesel Benz]

The VIN is WDD2210222A190558 - sorry as I forgot to re-mention it from the last page.

I read a thread on another forum about a W221 S350 petrol where someone mentioned it has the coolant and screen wash (temperature?) sensor wired in series and if one of the two sensors go bad, it can trigger a engine fan light ON and engine fan ON situation because the fan thinks the coolant temperature is too high or because it is detecting a faulty sensor and puts the fan on as a precautionary measure. If this is true, it surely must be wiser to replace both sensors and then see if the problem comes back - if it does then that can only mean one thing, the engine fan.

As mentioned, STAR is saying 1636-004 - Check component M4/7 engine fan - discontinuity of signal line. I take it discontinuity of signal line means no feed from a sensor right? If I am correct, it could mean there is a faulty sensor that is causing this symptom.

Thanks.

Yes, MB used to combine the coolant level sensor and the washer level sensor in series into one common circuit. On the 221 however both seem to be separately connected to the front SAM.

The M4/7 suction fan is directly controlled from the engine control unit. All relevant sensors are read by the ECU or SAM and signals are delivered via CAN if necessary. You should see an issue at your cluster gauge if the engine temperature sensor is misbehaving.

The fan unit should be A2215001193. Looks like it comes with the fan cowl.

Did you run any additional tests with the diagnostics tool, like try to set the fan on/off or at an intermediate speed?

 

[mbenz1]

Yes, MB used to combine the coolant level sensor and the washer level sensor in series into one common circuit. On the 221 however both seem to be separately connected to the front SAM.

The M4/7 suction fan is directly controlled from the engine control unit. All relevant sensors are read by the ECU or SAM and signals are delivered via CAN if necessary. You should see an issue at your cluster gauge if the engine temperature sensor is misbehaving.

The fan unit should be A2215001193. Looks like it comes with the fan cowl.

Did you run any additional tests with the diagnostics tool, like try to set the fan on/off or at an intermediate speed?

Thanks for your excellent support as always!

Ok, good news about the sensors then - so we can eradicate the screen washer sensor from the equation for the time being.

Engine temperature needle travels its way up to 90C as normal, however I have noticed on two occasions now that it sometimes takes about 5/10 minutes longer to reach 90C, but I put this down to the fan being constantly on hence causing the engine to warm up to 90C longer than usual or the weather. Is the engine temperature sensor in the coolant exp. tank or in the block or is there both a sensor in the tank and block?

Thanks for the part number. Just did a search on eBay and this part number comes up for a 2010 S350 CDI which is the same block as the 320 so that's good. Strange my local MB specialist gave me A2219066500 for the fan??

No additional tests unfortunately. My local MB chap kindly did a STAR check and printed the result out for me. Tbh I don't think they run additional tests as they have never recommended this and neither I have heard them mentioning this.

Today, we drove the car again and for the first time, the fan never went off. We had a couple of stops and as the engine was shut, the fan would go off and as the engine was turned on again, it would come on again! It never went off even after reaching 90C and strangely enough the temperature remained stable at 90C! I was expecting the engine temp to go down due to the fan being on at full speed but the needle was still!

 

[mbenz1]

Diesel Benz - could you please provide the part number for the coolant reservoir in your convenience?

Also, would there be any way of testing any of the pins inside the harness that connects to the coolant tank? If so, what should I be looking for and on what pin?

 

[Diesel Benz]

Diesel Benz - could you please provide the part number for the coolant reservoir in your convenience?

Also, would there be any way of testing any of the pins inside the harness that connects to the coolant tank? If so, what should I be looking for and on what pin?

The fan part A2215001193 comes from (off line) EPC. EPC does not know this A2219066500 part, it could be an updated part that has been released after 2018. I should have checked from Parts info but I prefer the stable off-line EPC, Parts info does not seem to be working at the moment. Should not be a scheduled maintenance.

The coolant expansion tank part number is A2215000349 (from EPC!).

Coolant level switch connector pin assignment in the attachment.

 

[Diesel Benz]

Parts info is up and running. Odd but it does not recognise the A2219066500 part. Then again it appears on a web shop as a part replacing A2215001193:

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[mbenz1]

The fan part A2215001193 comes from (off line) EPC. EPC does not know this A2219066500 part, it could be an updated part that has been released after 2018. I should have checked from Parts info but I prefer the stable off-line EPC, Parts info does not seem to be working at the moment. Should not be a scheduled maintenance.

The coolant expansion tank part number is A2215000349 (from EPC!).

Coolant level switch connector pin assignment in the attachment.

Thanks for this. Highly appreciated. Yes I just checked on a German parts manufacturer website (Febi Bilstein OEM for M-B and BMW etc.) and they also give 2219066500. I think you are correct in saying that it is a updated part number of the original 2215001193. So this means that there should be no issues in buying the original part unless the car came from factory with the updated part, which can't be possible as you mention this part is most likely released after 2018. I will go for the original part if its the fan that's causing the issue.

Thanks for the coolant tank part number and pin diagram. I'm not able to read the descriptors on that image as its very unclear for some reason. If I'm correct, there ate 2 GND pins 2 SIG pins and 2 temp pins (+ and -) but something is mentions before 'temp' which I can't read unfortunately.

Finally, what is the relation of the coolant level switch to the fan? Is it something along the lines of if the coolant overheats, its level rises in the tank and the level switch tells the ECU which then tells the fan to turn on?

Thanks.

 

[Diesel Benz]

Trying to attach a more readable diagram.

The main purpose of the coolant level switch is obviously for the cluster warning in case coolant level is low. I did not find any proper functional description of the fan unit, don't know if it defaults on when coolant level is low.

 

[mbenz1]

Trying to attach a more readable diagram.

The main purpose of the coolant level switch is obviously for the cluster warning in case coolant level is low. I did not find any proper functional description of the fan unit, don't know if it defaults on when coolant level is low.

View attachment 109788

That's perfect, its much more clear now.

Thanks, I will do some research and reading to find out what, if anything, can be checked on the pins with a multi meter.

 

[mbenz1]

Just thought it would be a good idea to have another look again under the bonnet, and surprisingly I found 'A 221 500 04 93' on the top RHS of the radiator shroud! Now, this is funny because this part no. does not match with EPC (A2215001193) or the updated part number (A2219066500), although I take it they are interchangeable...

In terms of the problem, I am leaning towards taking a small chance and buy a used expansion tank for under £18 on eBay and give that a go. If problem still persists then surely it has to be the fan... I've seen one on eBay for £150 UK seller (the complete fan including the shroud), which is not bad bear in mind the next price up is £170 from Spain and £200 from UK.

STAR says '1636-004 - check M4/7 - discontinuity of signal line'. What signal line is it referring to? The signal going from the coolant tank sensor to the ECU then to the fan or the signal telling the fan to turn on? My money would be on the signal line from the sensor...

 

[Diesel Benz]

A 221 500 04 93 has been replaced by A2215001193 which again has been replaced with A2215001193.

There is no sensor line to the fan unit. The connector has 4 pins, ground, circuit 87 power, circuit 30 power and a single control line from the engine control unit.

 

[mbenz1]

Thanks for the info.

I've gone and purchased a A 221 500 04 93 used fan unit and a used expansion tank unit.

Will suck out as much coolant from the exp. tank, replace the expansion bottle and fill up with coolant and check if the fault disappears (will leave rear battery disconnected during the job for 1 hour to hopefully reset the ECU)

If no luck, then will attempt to install the fan unit, again leaving the battery disconnected, and see if that cures the problem..

On a side note: today I drove the car and noticed something along the lines of what you mentioned in post #28...The car warmed up to 80C (fan light and fan constantly on) and when I accelerated with medium foot, the needle quickly jumped to 90C and the fan light instantly went off (but fan remained on). Then when I slowed down or approached the lights, the needle quickly jumped down to 80C and fan light came on again (fan still on). This would repeat as I accelerated and slowed down. Does this symptom point towards a faulty engine temperature sensor? If so, what would be the part number and where would the temp sensor be located?

(Normal engine operating temp is 90C)

 

[mbenz1]

Update (for the record):

Got a used engine fan from eBay and connected it to the car and still had the same problem - engine fan light on and engine fan turning on. So this meant it wasn't the fan. The next thing we did was get a used expansion/header tank off eBay as there is a sensor inside this tank that can go wrong. We connected the tank and this did not solve the problem either. Luckily we were able to return these 2 items back so not much lost besides the fees to ship them back.

The FIX was the following... It turned out to be a break in the 0.5mm2 Red-Black wire running from pin 58 in the N3/9 ECU (located at top LHS of engine bay, when looking at the engine) to pin 4 of the engine fan harness/connector. This was causing the ECU to turn on the fan as a precautionary measure because it was not aware of what the problem was and it did not want the car to overheat hence turning on the fan all the time...

We managed to identify this problem by doing some simple continuity tests from the ECU connector to the engine fan connector and discovered no continuity in this wire!

To fix the problem, we ran a new wire between both connectors using the Red Splice connectors and then the error code disappeared and engine fan stopped turning on all the time. A big thanks to DieselBenz for his great support on this forum.

Hope this helps others. If in your case it does not turn out to be a broken wire, then I would recommend getting a 'engine fan speed control test' done by anyone with STAR to establish if the ECU is communicating with the fan. If the fan speed test does not function, that could most-likely mean the ECU is faulty and need replacing (or repairing, if possible).

We also changed the engine coolant temperature (£7 for a OEM Febi Bilsten part) as a precautionary measure...

 

[Hasic]

Hello, i have a Mercedes w212 2015 year and i have problem with the ntg comand, playing music with bluetooth is excellent but sd card, usb stick and CD is not readable. I tryed all format of music but not readable