W211 Stero, indicators, lights, parking sensors etc..

[deanflowers]

Hi ive got a W211 2004 E320CDI.

If i leave the car for a couple of days then the stereo will not work (MB logo appears then goes out). When this happens the parking sensors go off every minute or so, the indicators some times miss a flash, the passenger sidelight flashes, the interior light illuminates randomly and the dash says SRS malfunction. This has happened twice before and returned to normal after a week or so but this last time its been like it for 2 weeks (the car does 1000 miles a week).

It has said convenience options disabled but then said restored when everything was working fine.

Ive replaced the rear main battery with another one i had off another car and also changed the auxiliary battery but no joy. Was thinking the aux battery relay as the next thing to change??

Any one had anything similar happen and know what the fix could be?

 

[deanflowers]

If i disconnect the main battery and reconnect it then everything returns to normal but then next time the car is started its back to everything not working properly

 

[John]

My immediate suspicion is alternator (assuming the batteries you've installed are known to be good i.e. did you test them?).

These cars suffer very easily from a lower-than-normal voltage and you get a myriad of random she-at. The fact that everything works normally once you reboot (!) the car might mean there is nothing fundamentally wrong with the things that aren't working correctly.

Turn your car to ignition key position 1, set the display to outside temperature and then press the dashboard reset button 3 times.

What voltages do you see when the car is off, and then after you start it?

 

[deanflowers]

When i checked the running voltage after changing the auxilary battery last week i was getting 13.2V

Today its 12.4V with the engine off and 11.9V running.

The auxiliary battery is a new mercedes one (not sure on its age though as i got it off ebay) and the battery now on the car is 8 months old varta so i assume they are both good. The auxilary battery i took off is reading 12.5V

Something i have noticed is that by taking the battery off for a few seconds and putting it back on restores everything except when i slow down the parking sensors are going sounding on red instead of displaying 2 yellow lines.

 

[John]

When i checked the running voltage after changing the auxilary battery last week i was getting 13.2V

Today its 12.4V with the engine off and 11.9V running.

The auxiliary battery is a new mercedes one (not sure on its age though as i got it off ebay) and the battery now on the car is 8 months old varta so i assume they are both good. The auxilary battery i took off is reading 12.5V

Something i have noticed is that by taking the battery off for a few seconds and putting it back on restores everything except when i slow down the parking sensors are going sounding on red instead of displaying 2 yellow lines.

That sounds too low. I was getting electrical glitches all over the shop with early 13s running (c13.2v) and late 12s off (c12.9v) (are you sure you have your engine running / engine off figures the right way round above?). With a new alternator, I'm now getting late 13s off and early 14s running. Mine is a 54 so around 10 years old and yours is an 04! I'm not saying it is that but highly suspicious...

Yes - your random parking sensor issue is what I used to get even when dry (although I also get that still when it rains - they need to be dried and have dielectric grease applied which fixes them in my case).

I'd also get things like:

1) Windows stopped working - fine after turning off and on again

2) Loud crack sound through the stereo and it would stop playing an MP3 disc for a moment and then carry on - randomly - then do it again

3) "Convenience features disabled" all the time

 

[deanflowers]

Yea the figures are the right way round. I will try an alternator and dry out the parking sensors.

I did 30K miles last year in my W140, plus a fair amount in my W210 and a W124 without missing a beat. This one seems far to clever for its own good. W211 is quicker and better on fuel but it has been hungry for parts the last 6 months ive owned it.

 

[John]

The fact you get a lower reading when your engine is running is odd!

I've had mine for 4 years now and it has only wanted a ball joint in that time up until 6 months ago.

Since then it has needed Airmatic pump, alternator, front anti roll bars, front suspension arms and rear subframes.

Once it is working as it should - it is a dream to drive though so keep going!

Below I should have said "I also got things like:".

I only get the parking sensor issue in the wet now.

 

[deanflowers]

Double checked this and i do get 11.9V on startup and it stays there until i pull off, then it goes up to 13.9V/14.0V. Do you think it could be this low startup voltage?

 

[John]

It sounds like it.

Your alternator sounds fine in that case.

I'd now be suspecting something leaching power from your batteries when the car is not running as you are experience quite a drop in a couple of days possibly?

I can try and remember to check mine Sunday night, having not used it since Friday evening, to see what the voltage is after a couple of days of not using it unless anyone knows how much the main battery is likely to drop after a couple of days of non-use?

 

[John]

When I turned my car off Friday night it was 12.8v.

This morning before I started it and it was 12.1v.

I can only assume it is the running voltage that matters although the 'convenience features disabled' error only came up once started.

Straight after starting it was 14.1v/14.2v.

So it doesn't sound like it is voltage causing your issue as your results are not far off mine.

My suspicion now is possibly an issue with the wiring loom installation. These were installed by robot until Summer / Autumn 2004 and then switched back to human-installation due to electrical reliability issues and glitches.

Or could it be a damp issue - are all the drain holes / fuses areas clear of water / damp?

 

[deanflowers]

I couldn't see any obvious signs of water but will check. Your figures are very close to mine though. I was thinking maybe a relay somewhere so by taking the power off for a second is allowing everything to work. Just an idea.

Mine does take a while to climb up from 11.9 to 13.9 so it could be the alternator.

Think this may be one for the an electrical garage i know who do lots with BMWs and mercedes.

 

[John]

Mine does take a while to climb up from 11.9 to 13.9 so it could be the alternator.

Yes, could still be that as these things are very rarely binary i.e. I had a slow deterioration over years now in hindsight.

Mine got up to early 14s pretty much as it started running.

I think these cars are on the limit of 12v!