Electric Headrest Fault

[sideshowbob]

My '88 Highline 635CSi has fully operational electric Recaro style sports seats.

All operations work correctly except for one fault and that is the drivers headrest does not operate. It has been like this since I bought the car some 9 years ago and I have now decided it is time that I investigated this fault.

I have taken the seat back off and removed the motor and to my surprise the motor when wired directly to a battery works correctly, infact it is very quiet and smooth, so far so good.

However when temporarily reconnected to the cars wiring and the electric up and down buttons between the seats are operated the motor does not work !!

What does happen is that I can hear a clicking noise under the drivers seat every time the buttons are depressed, am I correct in thinking that this is a relay or something.

Additionally, where the drive to the headrest comes out of the motor there are 3 brownish wires that terminate in a small plug....are they something to do with the memory function...or what ?

I am not that good with electrics but there seems to be a failure to get electrical power to the motor.

Any help would be appreciated as it has now started to annoy me.

I might add that if I can get the motor powered up in situ. I will then investigate whether or not I have to mod. the drive as already mentioned by other members.

Thanks in anticipation

[sideshowbob]

Further to the above I have noted that the 3 brown wires that go into the plastic unit that is part of the motor mount is described as a voltage regulator. Am I right to assume this unit is in some way linked to the under seat relay and controls the range of travel of the headrest.

Does anyone have a wiring diagram for the electric seat operation or any experience of removing the drivers electric seat.

Thanks

[86_6series]

It's a relay inside the memory box #6'

https://www.realoem.com/bmw/enUS/showpa ... Id=61_0315

Pg 5200

http://wedophones.com/Manuals/BMW/1986% ... Manual.pdf

[sideshowbob]

Thanks for that. When I press the headrest up/down button I can hear the relay click in the unit under the seat.
However no power is going to the headrest motor.
I am assuming when I hear the relay click it is working and the motor should work.

If this is not the case, can anyone on the forum suggest what else might be wrong.

Thanks

[K1W1]

Caveat - I have the sport seats ... however I had similar symptoms on the passenger seat. The head rest wouldn't move up or down.

I removed the motor - with cable drive still attached to the headrest mechanism. And with the cable straighten out it worked !

Twisting it various ways (as the drive cable follows the pattern of a large "U" i could make the motor work or not, based on it binding internally somewhere I presume.

Impressed it didn't burn the motor out actually. Maybe your issue is as simple ? cheers Julian

[ron]

Further to the above I have noted that the 3 brown wires that go into the plastic unit that is part of the motor mount is described as a voltage regulator. Am I right to assume this unit is in some way linked to the under seat relay and controls the range of travel of the headrest.

Does anyone have a wiring diagram for the electric seat operation or any experience of removing the drivers electric seat.

Thanks

You have PM.

[86_6series]

Open the link I sent you it's the ETM (Electric trouble shooting manual)

[sideshowbob]

Have managed to resolve the none operation of the drivers electric headrest that has been annoying me for quite a while.

After a discussion with another member...big thank you Ron ! I decided to bite the bullet and removed the electronics box from under the seat and then remove the seat.

This is where I found the problem, in the seat base all the wires to the headrest electric motor and the voltage regulator had been severed, probably originally badly routed and I think the forward and backward movement of the seat over the years had caused this problem.

So I spent a pleasant summer evening on the garage floor patching up the broken wires and attaching them to the seat base in such a way as they now travel with the seat.

Replaced the seat and bolted headrest motor and voltage regulator back in place and hey presto after many years of non-operation headrest on drivers side now works.

This means I now have new decals on switches and all electric functions are now working including three memory positions on the drivers seat.

Thanks for all your comments and hope you appreciate the feedback.

[ron]

Glad to be of help.