I'll hit some easy stuff off the top of my head.

I'm pretty sure that sedans didn't get SLS except for the 500E/E500.

For the driver's door situation the first thing I'd look at is the diode that plugs into the underhood fuse/relay box. I think 92s still have it. It allows stuff to happen when you open the driver's door without allowing power backfeeds. The diode can fail shorted or fail open. Symptoms are different for each failure mode. Get a pair of new diodes at Radio Shack for a buck and solder them into the old holder. Get the polarity right!!!

A light out warning is not uncommon when bulbs are replaced at differnt times. The module measures voltage drop across the two sides. A brand new bulb measured against an old bulb can be enough to trigger the warning even though both bulbs illuminate.

More later if the kids don't drive me berzerk tonight.

 

The transfer case should have fluid in it, and it should be ATF.
Check these...

 

@augapfel I think the light is on because BOTH license plate lights have no power. I'm prett sure I just need to pull the cover off the trunk lid and chase down the wires. Ick.

@Silversleeves Transfer case seems fat dumb happy and full of fluid.

I really think this must be some sort of electrical problem since I can't read the codes from the 4matic light. Especially since I have replaced the computer. Was just hoping that something out there might 'click' with the seemingly unrelated symptoms. Just not sure where else to look. I'm by no means an engineer, so something like this is just a PITA.

Thanks,

Doug

 

Doug,

Check your trunk wiring harness that is attached to the left henge. After nineteen years of flexing it may be flexed out. Look for broken ground wires (brn). Pull, clean all the contact surfaces, of your fuses. Replace every one with copper ones. Check under the drivers seat to see if the seatbelt, key in, etc etc relay is disconnected. Do you get dome lights with the passenger door opened?

Jayare

 

Jayare, Thanks. I figured I was going to have to pull the cover off the trunk lid and just dig in on the license plate lights. :-( As far as the dome and courtesy lights - they work fine with the passenger doors. Even the rear driver's side door works. I haven't checked the connections under the seat, but I suspect that they're fine since the heaters, etc work.

I'm probably going to have to do the same thing with the 4matic wiring. The warning light never goes off that I can tell. When shorting to test it just gets brighter. I would just blame a short in the dash lights were it not for the fact that it's just not working. Just wish I knew where to look. Without any indication of the problem, about all I can do is throw parts at it or put some tape over the dash light and forget it. :-(

Thanks,

Doug