backrest won't move
 

just need a few suggestions. "86 Carrera. backrest does not move via 4 position rear switch. r/r switch with new switch from Pelican. any suggestions on how to bench test the motor, seat is out of car? my Haynes manual schematics is pretty "sketchy" R/R front switch about 10 years ago and was a pretty simple repair, this one not so simple as a "bad switch". thanks

Run 12 volts to motor???

guess that is the big question, there are two motors under the seat which seems to raise and lower the seat itself and both work. does the seatback have its own motor "in" the seatback itself? there is a a connector that came with the new 4 way switch which plugs into a lead that seems to go into the seatback...…..is it possible that I would have to remove the seatback from the seat bottom and peel back the cover????? thank you for the response

Extremely likely to be the switch as opposed to the motor. I just went through this on my 928 which is basically an identical seat and control set up, I ended up putting power to the motors individually through some easy wiring just to be able to get the seat where I wanted. The correct and longer-term fix is to replace the seat switch. It is possible to repair the seat switch is but adjusting for brain damage on doing it I just replace them, let me not be the right answer for everyone

thx for the information. I replaced the 4 position switch with new, still did not work. I talked to a upholstery shop who did my headliner on my cayman and they seem to think the motor for the backrest is IN the backrest at the bottom. If I find out anything else will post

just a final followup. Went to Porsche Nemiga PET site (whatever that means) and downloaded the entire 1986 911 parts blowup for the entire car. Nice site, it is broken up by category and covers nearly all Porsches. site is
https://www.porsche.com/all/media/pdf/originalparts/en/E_911_86_KATALOG.pdf
on pg 327 it appears the motor is located IN the backrest...….

That Motor should have a Grey/Black wires going to the switch, if it’s the power back. Try pins 6 and 4 to test.

Following. I have the same exact issue.

Here the link to my motor thread.

http://forums.pelicanparts.com/porsche-911-technical-forum/1049074-anyone-open-up-bosh-seat-motor-if-so-ideas-crimping-shut.html

the bosch motor is 0 390 206 693 and available for around 50$, google. since my seat is out of the car, I wil take it up to an automotive upholsterer who repl my headliner in my cayman and have him fix a few small tears and remove the seatback cover to get to the motor. I did apply 12v to the pins listed above and applied 12v to the power cable that appears to go to the seatback motor. motor was dead silent. perhaps I get lucky with a bad connection. this has turned into one PITA. will let you know how it goes

Yup... I pulled my seat and switches apart and swore a lot.. Of course it quit and blew fuses right after got it.. PITA..

just a final summary. once I found the Porsche diagrams of the complete car (link above in earlier response) it was apparent the seat back motor was indeed in the seatback about head high. I took the seat to the upholsterer who removed the cover on the seatback and it was mounted behind my shoulders. motor is same as the other two under the seat which can still be bought, for 200-300 from a Porsche dealer. My problem was not the motor but the 2 foot long power cable from under the seat to the motor itself. This can also be purchased for 69$ and 20 expediting fee from Germany., none located in the USA. the power cable should be here late this week. as my brother and I always say about working on our Porsches, nothing is easy. thanks for all your help!!!!

Update on my car as I was having the same issue:
My 86 Carrera was at the independent shop getting a new clutch and I mentioned the rear seat back was not working. They took the seat apart and found one of the wires going to the motor in the headrest of the seat was frayed and not working. They replaced the wire and now the backrest is working great. I was impressed by how smooth it was actually.

My seat has the same issue. I plan to remove the seat and take it to an upholsterer just to take the leather seat off. My switches work, as I can test them and they work fine. It has to be the motor or the wires. I suspect it is a bad connection.

Now I just need to find a good upholsterer willing to remove the leather, and put it back on when the motor is fixed.

Why couldn’t you just repair the cable, or fashion a new one?

In my case, this is exactly what my shop did.

And I'm guessing the parts cost was a lot less than $89!

Yes, but the labor cost was way more than $89! Oh well, at least it's working and I don't have to worry about it anymore.