1990_GT_SC

Hi guys,

How are you doing in times of pandemic? I'm new to Rennlist and I've just bought a US black on black 1990 928 GT.
Since the driver's seat bolsters were useless and I did not want to have the seat reupholstered, I bought a mint used driver's seat from the UK with a seating function including relay, switch etc. which happened to have barely been used.
Problem is :
1) safety belt buckle is on the wrong side (left)
2) it's missing several plugs, connectors etc.

old US driver's seat with black memory control box


memory seat plug from underneath driver's seat inside car


backside of memory driver's seat plug under in car.


GB driver's upper seat with only two plugs


GB driver's seat with only one seat heating plug


6x GB seat heating plugs (number four and five from left go into black control box; green plug goes into bottom seat heating; third one from left goes into heating relay)


underneath US driver's seat frame and memory wiring (which is missing in GB driver's seat)


top of US driver's seat and memory function (which is missing in GB driver's seat)


memory control box from US driver's seat.




US driver's bottom seat from another perspective.


GB driver's seat with heating relay and connector, two black plugs (top right), one 2-pin board (bottom left) and one male plug underneath two parallel black plugs.


I then decided to take the lower and upper seat off the UK frame and put them onto the US frame while using the plugs, connectors, relays and memory control box from my old US seat.
Now I've realized not only does the wiring differ, but I would have to dismantle the upper US seat and take out the wiring to fit them into the GB upper seat, which would likely mess up the new mint leather seat.

I'm not desperately looking for a seat guru who could help me change the wiring or/and connect the seat and heating properly ( Adam mentioned ALAN?).
a) For now I've got only two small plugs coming from the upper GB seat and one from the lower GB seat.
b) I've got several plugs, connectors, control unit and two relays on my US frame and memory driver's seat.
c) I've got several plugs and connectors, and a relay and a switch for my seat heating.
Any help would be much appreciated. Lots of pictures been taken to exemplify the issue.

Thanks a lot and take care,

Alex

Alan

If you only have 2 plugs from the backrest of the GB seat then seems one is for heat and the other backrest angle which suggests you don't have lumbar or memory there - did you have lumbar on the USA seat? Did you lose the plug shell for the 14pin connector on the seat? The non-memory seat back won't work with memory - all motors need a position feedback potentiometer to work with the memory controller which the GB seats won't have. The memory unit you show is capable of memory on all functions (including lumbar), and if you have the same thing on the passenger side that is capable of memory on all functions (including lumbar) too.

I'd have someone (or yourself) swap just the seat covers & heaters over to the USA hardware, its time consuming - but not particularly difficult, the functional result will be much better. Plenty of upholsterers would be able to do this for you (or with you)

Non-memory seats have different simpler connectors, and seat to car plug connections. The GB seat heating alone can easily be adapted

Alan

1990_GT_SC

Hi Alan,

thanks so much for your reply to start with. I've been working myself through seat covers, seat hardware and refurbishing the rails and parts of my US driver's seat parallelly for the last 4 weeks, and it's the very first time I'm doing this, so I'm very thankful for the electrical insight since I I do not understand binary (just yet) and I don't have or understand the seat wiring diagram :-(

My US driver's seat does not have lumbar function nor the heating function. Th GB driver's seat was missing all the memory unit, memory relays and all plugs and connectors except for the ones shown on the picture. It did not have lumbar either and was missing the two electric side switches, but it had the heating function with the heating switch and a third free switch spot, so I upgraded the switch frame from two switches to three. Only issue here is that I had to insert them upside down into the US seat frame onto the left side, so the forward/backward switch is in the back while the height and angle switch is at the front. I did lose the intermediate 14-pin shell going from the US driver's seat into the 14-pin car connector, but fitted the male into the female pins and taped it.





I also switched the heating switch position from upside down to regular.

That's how my US driver's seat frame looks like at present with several connectors unplugged. Freaky to say the electric function would then start to go crazy when using them, reseting themselves after 5 seconds. Even the electric mirrors would do so. And only the left seat rail would work, not the right one.
I also realized that once I disconnected and took the US driver's seat out of the car, I lost the forward/backward function on my passenger seat? By the way, my passenger seat looks basically the same as the GB non-memory driver's seat, so no black memory unit nor relays underneath either. Thought I could swap it to the driver's in the meantime and drive my 928, but no...





To understand the 928 seat electrics better, could you please explain to me what these switches shown in the following pics are for?


US backrest seat single plug on plastic board?



US backrest seat add-on plug going into backrest?



US backrest with hidden plug in right bolster going up to center headrest?


L-plugs 4, 5 and 8 coming out of US backrest going into black memory unit?



two thin short top white plugs and two longer bottom white plugs inside car underneath US driver's seat?



Forgot where this plug coming out of underneath US driver's seat inside car is plugged to?



two plugs left from heating wire taken out of GB driver's seat and inserted into US driver's seat frame - one (green) connects to bottom GB heating seat stripped off GB frame - and the other one?



this one comes from the heating switch with a black 8-pin connector board?



This is where I screwed the heating relay onto the US driver's seat frame since there was no more space underneath.



That's the two unplugged connectors from the US driver's seat left due to plugs missing in GB backrest. The black 2-pin plug is to connect to what (power or safety belt signal?)



FINALLY, how can I unloosen the two backrest levers to strip down the last upper leather and foam part off the US and GB backrest and swap them as you suggested? Did not want to force it and break them.


AND... I have absolutely no plan how to connect and get out the heating wires out of the GB backrest and wire them again to the US driver's seat :-(
I'm sorry for all the questions - I realize the seat electrics is so time consuming, but I'd like to understand it still to be able to do it myself next time.

Thanks a bunch, Alan :-)
Take care,
Alex