Driver's door will not lock with key

[FEP]

For too long I have been reaching in from the passenger side to lock the driver's door, so yesterday I decided to fix it.

Car is pre-facelift 325i Sport. Central locking has long been history and the actuators are either disconnected or do not impede the mechanism.

In the end I found it simplest to swap the passenger and driver's door lock barrels as it was clear that something was broken with the driver's one. Of course the barrels are handed so on the passenger one I dove out the barrel securing pin and refitted the arm that connects to the mechanism so that it was rotated by 180º. I now have a non functioning lock barrel on the passenger side which is no great hardship.

On my car (no idea if this is how it came from the factory), the passenger door lock is a simple affair - turn the key one way and the arm pushes the mechanism up (unlocking), turn it the other way and the arm pushed down (locking).

The driver's door lock however has many more parts, including a ball bearing, a two part arm, a grooved lock spindle etc etc. When replacing the driver's side barrel in the passenger side, it was not possible to just rotate the arms by 180º and I had to bend the central locking microswitch plate out of the way to get it all together (remember - the C/L is history anyway).

I have now figured out that the problem with my driver's lock barrel was a missing spring that connects the two arms.

So my reason for this post is, apart from perhaps helping future forum searchers to figure out their issue, can anyone tell me what is with the complicated driver's door mechanism?

It would seem that the effect of the sprung mechanism, which means that when locking the driver's door you're doing so via a compressing spring, is no more than making the action feel a bit cool.

Can this really be the justification for the over-engineering? Why does the passenger door not get the same luxury?

[BenHar]

It's to activate the deadlocks when turned 90 degrees.

Deadlocks won't work without central locking.

Ben

[FEP]

It's to activate the deadlocks when turned 90 degrees.

Deadlocks won't work without central locking.

Ben

Deadlocks? Are you saying that the C/L activators have two states one of which is deadlocked? In which case surely there would need to be two microswitches which there don't appear to be.

Still doesn't explain the fancy spring arrangement on the driver's door only

[Brianmoooore]

There's only one microswitch in the driver's door and the deadlocks are activated when this is pressed and held in. When the microswitch is released, the deadlocks are released.
Do the job properly with the correct barrels, working actuators and working ECU and you will take the load off of the barrels and associated parts.

[FEP]

There's only one microswitch in the driver's door and the deadlocks are activated when this is pressed and held in. When the microswitch is released, the deadlocks are released.
Do the job properly with the correct barrels, working actuators and working ECU and you will take the load off of the barrels and associated parts.

Thanks Brian.

I did spend some time on the C/L some time ago. The door jam connectors are pretty bad and the proper (if not only) fix seemed to be new connectors and that seemed nigh on impossible to do. Indeed, I had all seats and carpets out to try to fix glitches in the loom to no avail. Given the damp getting through the scuttle/roof there doesn't seem to much point changing the loom without a reshell - etc etc, so the car does me extremely well as long as it squeaks through MOT's, and doing without C/L seems like a fair compromise.

I still don't understand this microswitch business. Even with the fancy barrel mechanism, how does the microswitch stay depressed and if it doesn't what is the point of deadlocks only whilst the key is turned?

[Brianmoooore]

The bits on the back of the driver's lock barrel are an 'over centre' type hinged mechanism. Turning the key through 90 degrees flips the mechanism over, and pushes in the microswitch, but it's so designed that turning the key back through 90 degrees again to remove the key doesn't flip the mechanism back again.
To unlock the car, the key is reinserted and turned 45 degrees in the other direction. This is sufficient to flip the deadlock mechanism back again, and release the microswitch.

[FEP]

The bits on the back of the driver's lock barrel are an 'over centre' type hinged mechanism. Turning the key through 90 degrees flips the mechanism over, and pushes in the microswitch, but it's so designed that turning the key back through 90 degrees again to remove the key doesn't flip the mechanism back again.
To unlock the car, the key is reinserted and turned 45 degrees in the other direction. This is sufficient to flip the deadlock mechanism back again, and release the microswitch.

Thank you Brian - those BMW designers are nearly as smart as you!

[BenHar]

The bits on the back of the driver's lock barrel are an 'over centre' type hinged mechanism. Turning the key through 90 degrees flips the mechanism over, and pushes in the microswitch, but it's so designed that turning the key back through 90 degrees again to remove the key doesn't flip the mechanism back again.

I didn't know that. I just pull the key out with it turned 90 degrees so the slot is horizontal.

Seems to work .

Ben