I am hoping one of the MB techs can tell me what I am up against -

I get two malfunction messages when the exterior lamp switch is turned on:


Tail light, L Check Lights!

Tail Light, L Check Lights! Backup light on!

I removed the tail lamp bulbs from both sides and checked them out of the socket with a variable DC power supply. The bulbs are good. All the other bulbs check out fine as well.

The bulb carriers are clean, intact and no corrosion on the contacts. The wiring harnesses are also good as far as can be seen.

The owner's manual shows the very bottom outside bulbs as the tail, parking, and side marker lamp bulbs. These are the ones that are not functioning on my vehicle. Instead, the brake light bulbs are illuminated at a low voltage and being used as tail lights. I think that is what the "backup light on!" message is saying.

This leads me to believe that the problem lies elsewhere than in the bulbs or the carrier assemblies. Maybe the exterior light switch itself?

The owner's manual recommends getting to an MB dealer as soon as possible. Good advice?

Thanks for any assistance. WR