Yet another central locking question.

[BenHar]

1990 325i cabriolet RHD.

From the driver's door when I turn the key an eighth turn anticlockwise it should lock the doors but it doesn't.

When I turn it a quarter turn all doors lock and deadlock.

All doors unlock when I turn it from the quarter anticlockwise to the eighth clockwise position.

I can't work out what is supposed to actuate the locks for the eighth of a turn action.

Any advice, please.

Thanks
Ben

[Brianmoooore]

Locking (driver's door) is initiated by a switch built into the lock motor. Yellow/blue is connected to blue and/or white, via a couple of blocking diodes.

[BenHar]

I think the lock motor must be duff in some way. I'll try another one.

How does the short turn of the key actuate the motor? Does it physically move it?

Thanks
Ben

[Brianmoooore]

Does it physically move it?

Yes, the mechanism starts to lock as it would in a car without central locking, but as soon as the switch closes, power assistance from the lock motor takes over.
Wear in the linkage, especially the alloy piece on the back of the lock barrel, can limit the movement and cause problems.

[BenHar]

So maybe the motor just needs adjusting so that the key turn moves it?

The lock barrel mechanism seems to be in good working order.

Ben

[Brianmoooore]

Motor is mounted in slots, but if there's too much slack you may cure the locking, but then find it won't unlock. The steel 'jaws' that the alloy peg sits inside can be closed up a bit, or bent sideways to line up with a less worn bit of the peg.

[BenHar]

I've got the lock out at the moment.

Moving the "steel jaws" by hand doesn't trigger the motor.

I'll have a go at adjusting it.

Thanks, Brian.

Ben