W210 bulb out warning

[Chris Merc E320]

Re: W210 £20 CDI Avantgarde estate 2000 model.
Has Bosal towbar and electrics fitted.
Keep getting bulb defective warning on the dash, checked car bulbs noticed N/S rear brake tail light not working.
Checked bulb - ok?? changed it for MB genuine one, all ok since Saturday - went out today put foot on brake bulb defective warning light appeared.
Any ideas please.

 

[markjay]

Not sure about MY 2000, but the bulb checking is done mow days over CANBUS, so any additional circuitry added to the brake light system can affect it.

I suggest you take the car back to the people who fitted the towbar.

 

[Chris Merc E320]

Thought it may be to much of coincidence but was not sure - will return, weather permitting.
Also occasional rear sensor activation on O/S rear which started recently, very occasional and generally clears when reverse deselected then reselected. Or could this be a dodgy sensor?

 

[Tiff]

 

[Chris Merc E320]

Thanks Tiff, re: connector pic - is that what you think may be causing my problems?? Apologies re text - car is E320 not ....£20 ....typo.

 

[Tiff]

Most towbar fitters use Scotchlocks, and these cause lots of problems with bad connections,especially if they get damp. Try and trace the towbar wiring back and find where all the connections are made to the tail lights, and check all those connections. I always change bulbs in pairs on cars with bulb failure warnings, as I've found sometimes 2 different makes of bulbs can be enough to cause the light to stay on as the resistances are slightly different.

It could also just be bad luck. I've had a run of blown bulbs on the Vito, with no cause, just a simple case of the bulb burning out.

 

[Chris Merc E320]

Thanks Tiff, will change bulbs, check connections once snow cleared (just starting to fall here, forecasters issuing weather warnings for here tomorrow).

 

[Dieselman]

I suspect the lamp holder.

 

[Tinkerer]

Interesting DM, I have a towbar fitted ,which I do not use, and every 6 months get a bulb failure when I put my foot on the brake, on checking the bulbs there is no problem but eventually I get a bulb failure! Do you think that it is a bad contact that causes this and if so is there anyway of checking it?

 

[Dieselman]

The lamp holders can make poor contact to the lamp unit contacts, sometimes enough to melt the plastic lamp unit.

 

[Chris Merc E320]

Time for a terminal clean?