Electric seat connectors (W124)

[Bimmer-Bob]

Recently swapped Sportline seats into my W124 - awesome upgrade, except for one small quibble. The passenger seat was complete plug-and-play, but the driver's side was a little more work - the donor car had seat memory, mine did not - so I had to swap bases on the seats so that I could hook up the seat to power with the stock wiring harness.

So far, so good (mostly); all the motors seem to work save one - the one that controls headrest adjustment. Can someone remind me which connection under the seat controls the headrest motor, so that I can focus my troubleshooting a bit more?

One plug in particular kind of irks me - it's sort of a "Y" that comes out of the seat, with a black connector on one side, and a red connector on the other, and I can't really figure out what goes where. I only have one matching black connector to plug into.

[jay_bob]

From the ETM:
Drivers headrest adjuster motor wires (thicker 1.5 mm2) solid pink/pink-green
Sensor wires (thinner 0.75 mm2) red/yellow-red/brown
This is connector X5 on the control box

The y-connected harness is likely the seat belt buckle. The black connector is the "fasten seat belt" nanny buzzer and the red connector goes to later SRS control modules to determine if the drivers seat belt is fastened. 92 300D should have a passenger airbag, so look around for the red connector from the air bag harness under the seat.

Electrical troubleshooting manual available online at either startek or w-124zone.com

[Bimmer-Bob]

Originally Posted by jay_bob

From the ETM:
Drivers headrest adjuster motor wires (thicker 1.5 mm2) solid pink/pink-green
Sensor wires (thinner 0.75 mm2) red/yellow-red/brown
This is connector X5 on the control box

The y-connected harness is likely the seat belt buckle. The black connector is the "fasten seat belt" nanny buzzer and the red connector goes to later SRS control modules to determine if the drivers seat belt is fastened. 92 300D should have a passenger airbag, so look around for the red connector from the air bag harness under the seat.

Electrical troubleshooting manual available online at either startek or w-124zone.com

Thanks for the info. I think I know which wires come from the seat motor, but I'm not sure where they plug into - is it just the main plug, or is it separate? On the passenger side it looks like it plugs in between the big rectangular plug and the smaller square plug, if that makes sense. But I don't see the same type of connector.


Also, my car doesn't have a passenger airbag - kind of weird, talked about this with someone else before. Anyway, I have everything hooked up and working on the passenger side, it's the driver's side that is the issue. And I'm not getting this missing red connector thing. Gonna take a real good look at the passenger side again and see if I can emulate everything - it's a little challenging because the wiring coming from the seats doesn't seem exactly the same.


Thanks again.