What started as a flickering headlight is spreading like a cancer!

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gramey

Active Member
Joined
Jul 8, 2016
Messages
387
Location
Ipswich, Suffolk
Car
2003 R230 SL350 Tellurium silver
My problems began with a flickering nearside headlight but has now started spreading to other areas so any help would be greatly appreciated, I initially replaced the bulb, then the igniter, then the ballast on the headlight all to no effect. Then this evening the lights in the passenger door for the seat controls started flickering, although subsequently decided to stay on, this was followed by the script on the dash of 'consumer electronics offline' , which had randomly come up on it's own two days previously and I'd fully charged the rear battery.

There is also a smell that I would describe as similar to burning plastic in the engine bay, but for the life of me I cannot find where it may be coming from and this may in fact be hot oil from a slightly weepy rocker cover gasket?

I've checked for water in the airbox and the drains either side just ahead of the front windscreen suspecting possible water ingress but all these are clear, so if anybody has experienced this and can point me in the right direction it would be greatly appreciated.:):)
 
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Am not an expert but smell of burning plastic combined with your electrical faults would seriously worry me , I would not drive it but disconnect the battery (S ) and get it taken to an MB dealer or Indi for a proper inspection. Hopefully a forum member with more technical expertise can give you more specific advice - good luck !
 
It might help if you gave details of the vehicle?
 
My apologies it's a 2003 R230 SL350.
I would suspect the alternator or the belt, for electrical faults and burning smell but best to get on Star at an indie for proper diagnosis.
 
It might help if you gave details of the vehicle?
My apologies it's a 2003 R230 SL350 :)

I've had the lid off the fuse box on the drivers side near the base of the windscreen and all appears to be fine, the smell I'm getting definitely isn't coming from there.🤔
 
My apologies it's a 2003 R230 SL350 :)

I've had the lid off the fuse box on the drivers side near the base of the windscreen and all appears to be fine, the smell I'm getting definitely isn't coming from there.🤔
I would be tempted to take out all of the fuses one by one in the SAM, check for integrity with a multimeter and also check the connections for any sign of corrosion on terminals /relays etc etc

I had similar symptoms on a C Class where the rear SAM had some water ingress and cauced some corrosion on terminals.

Once dried and cleaned it worked perfectly.

New SAM units are not horrendously expensive and often 2nd hand bags can be found on eBay but you have to ensure that part numbers match and they may need coding.
 
Try a voltage drop test between ground points and Batt Neg terminal, 0v ideally, anything over .1v should be investigated. Poor contact, corrosion , loose or broken cable strands.
 
I would suspect the alternator or the belt, for electrical faults and burning smell but best to get on Star at an indie for proper diagnosis.
I checked the alternator this morning as suggested, initial start up consumer battery showed 11.47 volts and the 'consumer electrics offline' inscription came up.
Main battery showed 12.49 volts straight afterwards.
I went back to the consumer battery and checked again by which time it was showing 13.0 volts so I'm assuming the altermator is OK but possibly the burning smell is indicating a short somewhere that's draining the battery at standstill and causing my problems when running?
The only problem I have is I have no idea how to track it down?🤔
 
Maybe worthy of a mention or not but the nearside headlight works fine for several minutes when you first turn it on before flickering and going off.
If you turn the lights off for around 10 minutes it the process repeats itself, fine for a few minutes and then goes off again.
If there was an outright short somewhere I would have thought it would the headlight would not reset itself so to speak?
 
That's what an auto electrician does for a living - probably cheaper in the long run because leaving it could cause more expensive problems very quickly
I understand that but the best independent auto electricians here said to take it to my local indy as it would need a Mercedes diagnostic on it.
Unfortunately they're closed due to contracting coving, I can't get an answer from Alex Crow and the main dealers are booked up for weeks. 🙁
 
If I bought the latest icarsoft diagnostic gizmo does anyone know if that would delve deep enough to give me an indication of the problem or am I stuck waiting to get hold of someone who has professional diagnostic equipment?
 
Didn't realise you were close to Alex Crow - that is the answer. I have had nothing but excellent service at very reasonable prices from Alex and wouldn't take mine anywhere else. Keep trying them.
The issue with an iCarsoft id that it will read codes but doesn't go very deep so if it is a complicated issue you will need live data and better diagnostics.
 
Didn't realise you were close to Alex Crow - that is the answer. I have had nothing but excellent service at very reasonable prices from Alex and wouldn't take mine anywhere else. Keep trying them.
The issue with an iCarsoft id that it will read codes but doesn't go very deep so if it is a complicated issue you will need live data and better diagnostics.
Excellent advice.

iCarsoft is a very useful tool as said like Star.

The real skill is interpreting the fault codes as even with Star the actual cause may not generate a specific fault code but may generate one that allows someone wiith experience to know where else to look.
 
Just to eliminate the possibility of an intermittent fault on the voltage regulator, could you put a voltmeter on it while the flickering is happening to check that it isn’t intermittently overcharging.
The smell could be the battery cooking - once you know it you know it.
 

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