E28 central locking

[teatime39]

I’ve had a few e30s and know the central locking on my 1987 e28 is very similar, I’ve located my problem to the passenger side actuator however with the fuse out I tested all the terminals to it and found they all ground to earth, cables are , white, blue, blue/green, brown(assuming that is ground) and a white and black. Any help would be grand.

[Brianmoooore]

If the circuit arrangement is anything like an E30, then both sides of the motor will probably be earthed when things are static. This acts as a magnetic brake for the motors and helps stop the locks being hot wired.
You'll need to disconnect the locking ECU to test the motors, which are probably connected to the two plain coloured wire.

[teatime39]

Thanks Brian, so with the control box unplugged fuse out blue , white all clear the other 3 cables ground out and blue and white also have no resistance between them

[Brianmoooore]

Found a circuit diagram: http://www.autolib.diakom.ru/CAR/BMW/19 ... /fig09.pdf
As you can see, white goes directly to all the lock motors, but the blue only on the driver's door, the boot lock and the fuel flap lock. On the other three doors the motor connects to the blue only when unlocked. When locked , the motor connections for these three are white and black/white.

[teatime39]

Excellent work mate, I’ve been looking for that for three days, Ok , got everything going apart from the passenger side will open all the doors but won’t lock them and I’ve tried two actuators

[Brianmoooore]

Passenger door is locked by the microswitch in the bottom left of the circuit diagram. In an E30, this microswitch is mounted on the metal plate that's held in place by the large C clip that holds the lock barrel assembly in place. Probably a similar arrangement on the E28.

[teatime39]

Yes it’s the same arrangement, so a load across the two cables should lock the doors.

[teatime39]

Found it, micro switch cable severed in the door, white and black cable severed in rubber boot on the door , your help was invaluable, next valve clearance, thank you so much Brian , not sure where you are based but I’m a roofer so a favour for a favour.