I have a 1990 300TE 4matic wagon, my passenger seat & headrest control have been working intermittently for a while. Now the seatback is way down and won't come up. Forward and back seatbase control works. I took off the control panel and unplugged the module and cleaned it. Still doesn't work. All wires are connected. Guess I will get a voltmeter and test connections. Any other connections I should check? Any suggestions? Thanks.

Remove the seat ajdustment switch from the door. VERY CARFULLY disassemble the switch box. There are small springs and ball bearings inside so it's best to do this inside at a well lit bench/table. clean all the comonents and re-assemble.

I had a similar issue (and so have several other people) and cleaning the switch has solved the problem. Which is not to say that there isn't another issue, but cleaning the switch is a good step to take before buying a new one.

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Thanks. Tried this. Still doesn't work. Switched wiring so down is up and got my seatback up. Guessing this module/relay is bad (or part is) Thinking I need a new one...