Drivers window harness swap

[Z4 Blues]

Hi.
Need some expertise. My airbag light was on, took to the dealer and was told there is low resistance in the drivers side wire harness assembly. I replaced the harness, but the drivers window won't work. I put the original harness back in and it works fine. I returned the harness (parts guy a friend) and the second harness does the same thing.

I install it and no window action, put the old one back its fine?? I confirmed the part number via Real OEM (61126934607). 03/2003 / M54

NOTE: the passenger window and morrows work fine, just driver side won't with new harness...???

[Zulu4]

Can you check the resistance along each wire within the old harness to find which wire is giving the low resistance ? (For it to be low resistance, it must be shorting to earth or to another wire).
You could also check the output voltages on the end of the new and old harness when the other end is plugged into the car. This may give you a clue as to where to look for a problem.

[Z4 Blues]

Okay, I took the harness plugs apart and compared them. I found that two connectors are in the wrong place. After confirming the part numbers, build dates etc. the BMW parts guy is sending a "IDS" to BMW factory parts department to confirm the issue. This was the case with two new harnesses so there must be some confusion at BMW...

Ill try to upload pics

[Z4 Blues]

Zulu4, thanks for the reply. I did confirm voltage, which led me to take the plugs apart. I did not ohm out each wire, as I'm sure you know, sometimes moving it can change contact o I just decided to change it. While BMW is sorting this I threw the old harness back in so it's usable; however, my airbag light is back on...probably cuz I replaced the harness three times or is it a true fault? IDK...

[Zulu4]

Well done so far. Maybe you knocked (or unplugged) the airbag wiring with the battery connected. This can cause the warning to latch on. It may need an OBD device to clear it.