If you didn't know, you are supposed to used the european wattage bulbs, not the domestic ones. How's your brakelight switch?

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

After going through each bulb, finding them all good. The warning light disappeared. Arrrrgh! It was after I checked the left rear set of light clusters it went away. Maybe it's like what Manny said - just a matter of seating it in the socket.

Nevertheless, it's off now. Still annoys me that I haven't found the cause.

a tiny dab , on the contact points (clean) ,of each bulb [and clean contact
points of each socket]will make this annoying situation less likely in the future.

I have had problems with the contacts in the left rear tail light assembly too. I think it was corrosion, because when I took all the bulbs out and hit the contacts with some very fine grit sandpaper, it went away. Hasn't returned for about five years now.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

To ressurect an old thread, I have the bulb lamp warning lot on only when I turn on the lights on my new to me W124 Cab. I had a license plate bulb out, traced it to a bad wire in the hinge of the trunk and thought that would do it.

The license plate lights are now on, and all the other lights seem to work, but I still get the lamp bulb warning when I turn on either running lights or headlights. What am I missing?
Regards,
Jerry

You have found the cause...

...the metal rails inside the rear lamp housings that hold the bulbs in place vibrate loose over time. When that happens, there is a loss of "ground", barely visible as a slightly dim bulb here and there, but perceptible by the lamp indicator system as increased resistance.

When you went about inspecting the bulbs, you had reseated the rails by simply reinserting the bulbs firmly in their sockets. That restored a good ground connection, and all was well according to the system.

This one took months for me to solve...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

This post is only for Solidarity.

Yeah, I've been there too. For some reason, the cars I tend to dig are models known for (shall we say) "whimsical" electrical systems. My W126 is the car whose electrical system I can trust, at least; my Saab and my Cherokee, not so much.

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'88 300SE | Midnight Blue | 237k
'09 Subaru Impreza | red | 0k