Power Seats Driving Me Insane?

[JorgeSawyer]

Even though I've only had my 88M5 for a few months, the seats are incredibly erratic. The switches themselves are NOS and operating flawlessly, the fuses are in good condition, and the connections appear to be sound. The functions just come and go continuously, but each press makes the control device beneath the seat click. Sometimes you just move back. After that, it just keeps going. Every function comes and goes on a daily basis, and some have been out of commission for weeks at a time.

Since only the reverse function is functioning right now, I used a drill to relocate my driver's seat forward on the motor today. I went a bit too far forward, and now the opposite has also halted.The worst part is that I can't even turn it rearward by hand because the square bit receiver on the motor's end has also shattered. It is stuck.


Since it's all intermittent, I'm not even sure how to begin diagnosing; should I remove the seats and try to fix them? Since I am currently unable to sit in my car, I would like to discard these seats and order manual e30 sport seats with adapters. I'm just annoyed. The seat is frozen in place, so I can't even reach the front bolts to remove these.

Any suggestions? Is it crazy to replace out the M5 seats for manual e30 sport seats? This is where I see the adapters for sale.

I appreciate your advice!

[Etip]

Following as my M5 does pretty much the same. I believe it's the control modules under the seats. I pulled my seats and used contact cleaner and dialectic grease on everything but they're still just as erratic.  To the point I don't adjust them as I'm not sure it they'll go back. 

Hoping someone can give advice on how to fix the issue. 

[Fanclutchnut]

Could it be the wiring between the switches and the modules under the seats? I ask because our car needed these harnesses repaired as a result of an under car fire. It would require removing the seats, center console and carpets and padding to inspect. Not fun but might find your problem. 

[Blue Shadow]

Why is this in the M5 section?  It is a common seat issue.  Sure the M5 and M535i were the way US drivers could get sport seats but they were also in the 535is. More folks see the main tech talk forum than this forum. 

But let’s find out more about the seats movement. Are the motors running, or trying to when the buttons are pressed?  Are the gears, mechanicals requiring more power than the motors can deliver?  The seats in my Hartge don’t like to move forward, back unless it is hot out. I need to pull the chairs and do a clean and lube service on the mechanism. The motors click but no movement in cold weather. Sometimes assistance, like pushing the chair back while holding the go back button will assist the movement. 

Old grease that turns to glue is common in vintage automatic turntables from Germany and it seems this could cause the issue with the chairs.