No Reverse Light or Interior Light - 88 300E
 

Anyone have an idea of what to look for. I noticed that I don't have interior lights when I open the doors, but the bulbs are good because they come on when I turn on the lights. I also do not have any reverse lights and I've checked the bulbs and the fuse.

Any suggestions would be appreciated.

I can double-check my wiring diagram, but I believe these are separate problems.

The reverse lights might be the tranny switch. I have a manual, so no further comment.

The interior light issue is on my list as an active problem. The number of related posts indicate this is a common problem. Assuming the door switches are working, the culprit is said to be the so-called 'seatbelt buzzer relay', which does more than its name would suggest.
Another poster helpfully took pictures (thanks man!).
See http://diesel.web1000.com/5/

Thanks CSNow. I will look into that. I only thought they were related because they share the same fuse.

Will let you know how I make out.

Suggest starting with a voltage check at the door switches, and a continuity check through the switches. A pass would prove 1)The circuit is good, 2) the door switch is good.

Did they both stop working at the same time? That would blow my '2 distinct problem' theory...
It appears that the 2 problem lights have independent grounds, so unlikely culprit...

I'm not sure when they stopped working. I got the car with this problem and am sick of it now.

The light doesn't come on with the passenger door either though. It's weird because the buzzer comes on with the key in the ignition, but the dome light nor the lights on the bottom of the front doors come on.

I'll try your suggestion tonight. Thanks again.

According to past posts, it's the seatbelt warning relay if the lights don't come on when the driver's door is opened, even if they come on when the passenger door opens (this situation is what I have on my 87 300e). Do you get light from the driver's visor? I don't. To quickly & easily check the door switches, you should reverse them with the passenger door if the lights come on when you open them.

I am starting to believe that there may be multiple potential failure modes with this multi-function relay/buzzer.

This is based upon a search of posts, the wiring diagrams, and the fact that my silly seatbelt warning light stays on indefinitely if the passenger door is opened at some unknown elapsed time after the ignition has been turned off. (Not right away!).

Anyways, all roads (errr, wires) point to the relay/buzzer.
I'll report back my results when I get to it.