W202 Bizzare Power Seat Issue - Suggestions Needed!
 

Hey guys, new to the forum (and MB), but have done plenty of searching. Here's the issue with my new '95 C36, I'd welcome some suggestions. Remember, being the C36 these are the sport seats.

Passenger seat: doesn't move up/down on either adjustment, backrest doesn't tilt forwards. All other functions work, including backrest tilting backwards.
Driver's seat: backrest doesn't tilt forwards or backwards, all other functions work.

I've cleaned the switch, then checked for voltage at the seat wire harness plug. When I activate the seat switch, even the functions that don't operate, I can find 12V at the harness. All fuses check out good.

So, it appears my problem is either between the plug and motor, or with the motor itself. I can't hear the motor attempt to operate, so I don't think it's a stripped drive mechanism. However, one of the backrest motors will recline, but wont move forward.

Suggestions? My current plan of action is to remove the seat and test for voltage at each motor. I've read of issues with the relay, but that normally disables all seat functions. Plus, I have power at the seat, so I can't see how it's a relay issue. Probably unrelated, but my left side power mirror is also not working. Driver's side works well. Oh, the joy of German cars.:)

Your plan is correct IMHO. I had a headrest with the same symptoms (dead) and found a bad solder connection at the motor. Mercedes have good connectors but bad solder joints. At least in the 90's era.

Damn. I hoped someone would have a magic solution that would prevent me fighting with the heavy seat. Oh well. Thanks!

I did not have to remove my seat to work on the headrest. I just removed the back panel (2 screws). But your car may be different. If you can do that see if you can find out anything that way.

I remember those conveinence relays causing some weird problems with electric seats- Its the larger one under the cover in the trunk, but not sure if this will fix your problem. Just a suggestion if you can get one, to try and swap it out.

But if I have 12V at the seat plug when I activate the switch, that is AFTER the relay, correct? I guess I need to look at a wire diagram.

Your problem does not sound like the relay IMHO. The relay problem caused all functions to die together.

97 C230 with fore/aft drivers seat problem
 

My wife's 97 C230 has had problems for several years with the seat forward/reverse movement. Will move an inch or so then stop, after several seconds there is a sound under the seat like a reset then will move another inch or so. I found the relay in the trunk (there are 2 identical relays side by side). I exchanged the relays but still acted the same. I examined the relay under a magnifying glass but could see no cracks. Is there a relay at the motor under the seat. The front to rear movement appears to be controlled by the middle of the 3 motors. Getting ready to remove the seat to check the motor. Any suggestions would be appreciated.:confused:

Just as a guess, based on what you say, I would guess maybe something needs grease, and the motor is causing a thermal overload to trip. Or the thermal overload (if it exists) may be defective? It could be tricky to troubleshoot.

97 C230 W202 forward/reverse seat issue
 

Have been checking the forward/reverse seat issue again. Our local mechanic checked the relays (2). Swapped them results the same with either relay. Will move several inches then stop (thermal overload?) wait a few seconds then move again. Mechanic says there is 12 V+ at the motor, we both visually checked the relays for bad solder joints (under magnifier). Appears to not be the problem. What kind of grease is recommended, we have tried silicon grease, WD40, etc. No luck. Are all 3 motors under the seat the same, i.e. can they be switched or is the gearing intregal with the motor. Have thought about removing the seat to try a motor switch. Can a replacement motor be purchased? Any suggestions appreciated. Have read several posts about the relays but nothing if the relay is not the problem.
Thanks,
Barbarrosa1