Mercedes 230E (124) light problem

[MW]

My 1992 Mercedes 230E automatic has a problem with the bulb failure indicator lamp on the dashboard. When side or headlights are used, it always comes on even though all the exterior bulbs are fine and working properly. It happened once before, and was caused by using a 10 watt not the correct 5 watt rear bulb. When replaced, all was fine. I have already relaced all bulbs (except headlights), and ckecked contacts are clean, as a precaution. They were OK and one or two a little blackened. Still no joy as the dashboard light still is activated when the side or headlights are on. Headlights work normally on normal or main beam.
Any ideas?

 

[andy_k]

Have you checked the number plate lights?

if not it can be awkward to find but my guess is that one or more of the bulbs isn't creating a good contact - we had exactly the same problem and tracked it down to one of the rear lamps. It was a brand new bulb from Halfords we changed both rear bulbs for a pair of Hella ones and everything worked fine. so a little measuring of bulbs later showed that the Halfords bulbs were 0.2mm smaller in diameter - well within the OEM spec but obviously enough to cause a poor contact and set that dashboard warning light off. I hope that helps, I spent about 8 hours trying to work out what the heck was wrong but like you, the internals of my lamp clusters are spotless. clean more than just the contacts though, get to work on the sleeves where the bulbs are housed as well. Check the lights after dark and see if there is any visible difference in brightness from any of them, if there is a slightly dimmer one then that's the place to start looking.

Andy

 

[jaymanek]

Absolutely, the system is v sensitive - I changed just about every bulb untill i tracked it down to the rear sidelight - the bulb worked most of the time, but was a bit dodgy, after i changed the bulb all was fine.

By the way, anyone know about the interior cortesy/reading bulbs - When i replaced with standard 5W bulbs, they were really dim, the guy at motor factor advised me that i needed special mercedes Halogen interior bulbs. He had some at 6 quid each, did i get robbed??
All my other mercs have normal bulbs....

Cheers

Jay