I have an 87 SDL, and have been having electical problems with it for the last year. when I shut the car off for the night, the rear dome light will come on half an hour or so after I shut the car off. So, I thought I'd solve the problem by taking the bulb out. No joy, the battery still gets weak after a night. So, I unhooked the battery, and the battery was strong after the night when I hooked it back up and started it the next morning.
When the light comes on, I go out and open and close the back door of the car, and the light goes off for anywhere from 48-72 hours.
I had to rebuild the wiring harness for this car, and there were no problems with it for about 2 years after. Anyone have ideas??

__________________
All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic

There's no quick "solution" to this issue.

You're going to have to tackle it the long way.

Disconnect the negative battery cable and put an ammeter in series with it. Make sure all the doors are closed.

Read the meter.

Presumably, you'll get something above 100mA.

Now, start pulling fuses, one at a time, until the the current drops below 60ma (the clock and the radio).

Report back as to which fuse is the culprit.


Then, it gets more difficult...................

If the rear dome light was on are the lights on the bottoms of the doors on?

-Jason

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

About lights on the bottom of the doors, I dont' remember.

__________________
All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic

now I need to go get an ammeter. Or borrow one.

__________________
All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic

I'd just go get one. Twenty or thirty bucks will get a better-than-junk meter at Radio Shack, etc, and it'll be useful for many other things down the road.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL