IsaacSanFran

I own a 1987 190E 2.3L, and it's had some electrical problems since I bought it about a year ago. It's got a sunroof installed, but it doesn't work. Okay, I take that back, it worked ONCE, one time open, and one time shut. And it hasn't worked since. And when I open the glove compartment, the stereo (aftermarket (I know what you're thinking, but i checked it off with the wiring diagram from the Mercedes Repair Manual)) just turns off. Sometimes it comes back on after I shut the glove compartment door, sometimes it takes a while.
I didn't know what the problem could possibly be, until I was perusing through one of the introductions in the Haynes manual I have. It said something about malfunctions, and that there are generally only two causes: The questionable unit is defective, or the ground connection is bad. It really got me thinking. I had never considered a bad ground connection to be the culprit. I really should have considered it before, I almost went out and bought a new stereo amplifier because mine installed quit working, from the same problem: Bad ground.

Bottom Line: I was wondering if anybody else has run across this problem before?

Kynyption

It's not a fairly common issue to have a bad ground. However when aftermarket things are installed common issues go out the window. The best thing to do as a good test would be to pull your stereo and create a new ground and either make it temp to a known ground. Or do some preventative maintnence and make a good permanent ground to part of the chassis behind the radio or use the stock ground under the cluster. If you remove the panel under your steering wheel and look to the left youll see a mess of wires bolted to the frame. You can use that and run some new wire. See if that frees up your problem. If not you could be looking at a couple things. Have you checked the fuses? Have you tested the sunroof motor?

Get back to me

IsaacSanFran

I know the sunroof motor is in the trunk, on the driver's side (left, the car's American), but since the car is my daily driver, I don't have large chunks of time to tear into it. I have checked the fuses, and they all check out. The thing is, the fuses wouldn't be the problem, because the circuit is live. When I push on the sunroof button, to move it either way, it's almost like there's a bad connection somewhere. It could very well be a short-circuit, I won't rule that out either. But there is power getting around somehow.
And the incident with the glove-box, it could very well be a separate and isolated incident, but the symptom (the stereo turns off momentarily when I push the sunroof button, OR when I open the glove-box) is the same, leading me to believe that they are linked by one short-circuit, mis-wiring, or bad ground.

Kynyption

Well as you mentioned it is probably that there is a loose connection. I am going to assume you installed the radio or did someone else? Most wiring for all of that runs through that general vicinity. Its best with problems like these to try and isolate them one at a time to narrow down the culprit.

When you checked the fuses, did you remove them or just run a visual?

IsaacSanFran

I installed the stereo myself. I have one of the original repair manuals from Mercedes-Benz on a CD, and it illustrates which wires serve which purposes in the factory stereo, noting colors and wire sizes (millimetres, but I can roughly convert) for all wires. I checked that out, and all the wires are used properly. Well, except for the 'antenna' one. Now, I'm not sure that the aftermarket stereo uses the same voltage signals as Mercedes does for their power-antenna. The antenna never has worked either, but I never use the radio, so it normally wouldn't bother me. Until now...

Kynyption

Well, i would check the connections. How did you connect the two? Are any wires bare? It is safe to connect the ant to the aftermarket, however the wires for after market radio bare now could it have grounded? I know most after market alarms have a safety cut off that activates when a wire is gorunded incorrectly, especially when stereo connections ground.