E420 Driver's Door/Overhead Light
 

My overhead light (near the rear view mirror) is not automatically turning off after I close and lock the driver's side door with the key. The light switch is in auto (full forward) as it normally is. The red warning lights (seat belt, etc.) under the overhead light continue to flash as well. I also noticed that the rest of the doors are not locking when I lock the driver's side door with the key. When I reopen the door and move the light switch back a few clicks to get it to turn off (even with the door open), the red lights stop flashing after I lock the door.

Where should I start on this? All the fuses seem to be okay.

A possible related issue occurred last week when someone dropped a penny from the ash tray into the hole for the cigarette lighter (I don't smoke, so I removed it and I keep change in the ash tray) and blew the fuse #1. All the power windows stopped working until I removed the penny and replaced the fuse. Now the windows work fine.

Is it possible that the cigarette lighter shorted out some sort of relay or circuitry that is now causing the overhead light/door issues? The radio is no longer working either, but I'm not sure if that happened last week with the penny in the cigarette lighter or today with the door/light malfunction. In any case, the radio will not turn on and the antennae will not move.

Any ideas? Thanks in advance.

As with any MB with ceramic fuses, remove each one & examine closely.
Pay attention to fuses 3 & 9.

Yes fuses and corrosion place to start , when mine does that the door locks dont work correctly. It was a fuse I replaced them all with new copper style.

Thanks. I will start by replacing all the fuses. Are the stock fuses copper?

I went to the dealer and checked on their fuses. All they had in stock were kits with mostly white fuses (8A). I could have special ordered all new fuses, but it would have cost $58 total and they were not copper. Since eleven of my twenty four fuses are red (16A), I opted to look elsewhere and found Bussman copper fuses for $16 total. As I was looking at the factory fuse kit at the dealer, I noticed that there was one white fuse in the kit that was copper, while the rest were metallic color. I replaced all the fuses with the Bussmann copper fuses and the light and radio are working properly (for now).

Any opinions on Bussmann fuses?

I use the Bussman fuses, they replaced the contact area with copper which is where the problem stems from. They used a different material in the center than copper because copper that thin was not very consistant to pop as it should.

Thanks. For less than $20 and about 10 minutes of time, it was worth changing them.