Exterior Lamp Failure Indicator
 

I have a 1992 300D 2.5 Turbo. My exterior lamp failure indicator has been coming on, but only intermittently (but not in the brake light sense....sometimes it's on consistently, sometimes it's not). I have inspected all the lamps and all seem to be working properly.

Any ideas what else to check or what could be going on? Does the indicator come on when a lamp is about to go out before it actually goes out?

Thanks,

David Sherwood

Hi

The warning lamp only comes on when one of the exterior lamp is burned : if intermitent, unless it's a high beam lamp failure, you probably have a bad contact. On mine, the rear lights are prone to that : clean the contacts and check if the the spring contact puts enough pressure on the lamp. When inspecting the lamps, don't forget the license plate ones.

I'm not sure if M-B uses the same type of circuit for their Lamp Failure Warning, but in my BMW the warning circuit is very sensitive to the type of bulb being used. I think they use Resistance as a measure of a failed bulb and if you use bulbs with a brass base as opposed to a plated (silver colour) base, the warning circuit will trigger falsely. Changing the bulb to the correct type (resistance?) will cure the problem.:rolleyes:

Andy

note when it comes on
 

The indicator only comes on when the afflicted bulb is going to be used. So if a brake light is out, the indicator will only come on when the brake is pressed. That may help diagnos it.

I had an off and on light out indication. It was a loose bulb in the license plate lights (2 on my car). Very hard to see unless it was really dark.

As mentioned, be sure to get the correct bulbs. Wrong wattages will also trip the indicator.

Good Luck,

Chuck

Check the head light sockets, they may be melted due to heat.

Jack

My E300 has done that with a tail light. From outside the car it appeared fine. But when I pulled the light cluster, one of them appeared black inside. Still working, but about to blow. Replacing that bulb cured the warning.

Just removed my taillight housing this morning and found one small bulb blown. It was all the way on the outside corner of the housing, sort of on an an angle and hidden away.

Problem solved.