'91 S4 door lock issue
10-10-2021, 11:41 AM
#1
'91 S4 door lock issue
Howdy fellow enthusiasts,
I had previously posted about some issues I had with my door locks not working at all and ended up having the locks refurbished. They now work fine individually. The problem comes when I try to lock the car by locking the driver's door lock. When I turn the key, the driver's side locks correctly, but the pax side does not lock. I can lock the pax side from inside or outside by using the key. Funny thing is, after locking the pax door from the inside and then locking the driver's door by using the key, when I unlock the car from the driver's side using the key, both sides will unlock. So it seems a signal is getting to the pax door lock to unlock, but not to lock . Any suggestions would be welcome.
Jesse
I had previously posted about some issues I had with my door locks not working at all and ended up having the locks refurbished. They now work fine individually. The problem comes when I try to lock the car by locking the driver's door lock. When I turn the key, the driver's side locks correctly, but the pax side does not lock. I can lock the pax side from inside or outside by using the key. Funny thing is, after locking the pax door from the inside and then locking the driver's door by using the key, when I unlock the car from the driver's side using the key, both sides will unlock. So it seems a signal is getting to the pax door lock to unlock, but not to lock . Any suggestions would be welcome.
Jesse
02-01-2023, 08:35 PM
#2
Intermediate
Just came across this thread, and hopefully you've solved this now? If so please let us know the fix. If not, read on...
If both sides unlock when using the key in the driver's side then the passenger side lock/unlock solenoid and the wiring to it from the ECU controller are fine. The problem seems to be with the driver's door lock cylinder switch. It is not grounding the Brown/Red "prime" wire to the alarm and central locking controller when the key is turned to the 'close' position. This is also why the automatic closure of sunroof and windows doesn't happen. Jesse you'll need to investigate why the driver's door lock cylinder switch is not grounding that Brown/Red wire when the key is turned.
If both sides unlock when using the key in the driver's side then the passenger side lock/unlock solenoid and the wiring to it from the ECU controller are fine. The problem seems to be with the driver's door lock cylinder switch. It is not grounding the Brown/Red "prime" wire to the alarm and central locking controller when the key is turned to the 'close' position. This is also why the automatic closure of sunroof and windows doesn't happen. Jesse you'll need to investigate why the driver's door lock cylinder switch is not grounding that Brown/Red wire when the key is turned.
Last edited by Jonathan R; 02-01-2023 at 08:51 PM. Reason: Correction