DJFarmo

Hello,

I have a 2003 UK specification (RHD) E320CDI Avantgarde Estate (station wagon) which has done 100,000 miles. Recently, a message has started appearing on the dash saying that I have 6 malfunctions (both tail lamps, brake lamps and turn signals) and that the back-up bulbs have been activated.

In turns out that there are duplicate circuits in the light clusters that are mounted on the boot (trunk) lid that come on when a problem is detected with the normal lights (the fixed clusters on the corners of the car). The backup circuits seem to work fine. As a result, it's safe for me to drive around, but I would like to see if anyone can point me in the right direction to start tracking down the cause of this problem.

I am 95% sure this is down to a faulty connection or a short circuit, as I have witnessed the car switching between the normal and backup circuit. When I was looking at the rear lights one evening, the backup circuit was on and the car was stationary and turned off. Then, without warning, the normal lights started to flicker dimly back into life, but within a couple of seconds had died and the backup lights came on again.

Is there a common problem that is known to afflict the rear lights, else does anyone have any other suggestions based on experience?

Many thanks in advance.

paulv

DJ,

Just a thought, the US 03 E320/500 petrol vehicles have the rear lights driven by the rear SAM (signal acquisition & actuation module) unit -- I'm wondering if that is where your problem is. Good luck with it.

Regards,
paul...

shoebox

DJFarmo, Did you ever solve the problem? My wagon has the same error. Thanks

DJFarmo

In a manner of speaking. I'll try and explain what I remember, but this may not be completely accurate.

The problem I had was that I was getting 6 faults listed on the dash, relating to the three pairs of lights in the main tail lamp clusters. The car therefore activated the backup lights in the boot (trunk) lid.

If I stood and looked at the back of the car with the lights switched on, the brake light in the right cluster would briefly flash every 20 seconds or so. I disconnected both clusters then plugged the right cluster into the left side connector and saw the same symptoms. When I plugged the left side cluster into the right side connector nothing happened. I therefore concluded that the lighting board in the left side cluster was shot and so I bought a new board.

I installed the new board and found that I still had the same problem. I therefore check all the connections (i.e. wiggled the connectors etc.) and suddenly everything came back to life. I then decided to reinstall the old lighting board and discovered that it now worked fine too!

I guess the problem all along was a dodgy connection somewhere. However, I have not yet been able to properly isolate the issue. Just removing or disconnecting and the reconnecting the light clusters is usually enough to temporarily resolve the problem and get the lights working properly again with either the old or new board. However, within 24 hours or so, the problem normally reoccurs.

I really need to just get motivated and sort it out once and for all. In any event, the problem I have is caused by a faulty connection somewhere after the signal generator box in the boot.

I hope my ramblings are of some help to you!

shoebox

Okay thanks. I checked the boards and bulbs last weekend and it shows no signs of abnormalities. I'm going to trace the wires in the near future probably when I change out the hatch shocks. I'll post if I find out anything.