Central locking issue with passenger door

[ansys]

Hi all, I have an early SW20. I do not have a remote for locking/unlocking the car.

When I go to unlock the car with the key in the driver's door, only the driver's door unlocks. The passenger side does not.

When I turn the key to 'unlock' I can see the manual lock/unlock button on the passenger door (above the handle) twitch a little as though it wants to go. When I turn the key to 'lock', this button does not move/twitch.

This same thing happens if I'm trying to lock/unlock the doors using the central locking button on the inside of the driver's side door

I haven't been able to turn the key in the passenger side door lock for a while, and assume that's a separate issue. There was a time when I was able to unlock both doors from the driver's side while the passenger side lock wouldn't turn with the key.

Any thoughts? Could it be a broken wire in one of the door hinge wiring looms?? I've also read that some people have issues with the micro-switch at the driver's side lock cylinder? But if that was the case, why would I have the same issue with the button on the driver's side door arm rest?

Thanks all for your help!

[GDII]

It seems it is trying to turn but unable to. The fact the toggle twitches means you have power to the motor so wiring does not appear to be the problem.

You mention you can't use the key in the door lock? That to me means the lock is damaged and the motor can't move it because the key also can't.

Yes, wiring fails in the driver's door rubber boot a lot but you have a twitch so it has power. And yes, the microswitch can't break, mine did. It's a very weak part. But again, the twitch says it has power so the wires and switch are ok in your driver's door.

[ansys]

a bit of an update... I managed to get the key working in the passenger door cylinder now. I think there was just some debris in that centering spring around the cylinder that was binding up. A bit of forcing and WD40 on that spring seems to have done the trick for now.

With that, Using the key on the passenger door unlocks/locks both doors, but using the key or button on the drivers door does not lock/unlock the passenger door. As you mentioned, it seems like both doors seem to be "talking" to each other because I can hear the passenger door, and see the twitch when it tries to unlock.

I have a spare latch assembly since I replaced it a few years back due to the latch itself not really working properly. Because I could, I tried swapping out what I think is the microswitch on it, and that seemed to do nothing. The spare one could also be faulty I guess.

With all that, I suspect it is the motor in the latch assembly itself that is faulty? Anyone have experience with these? I'll probably try and remove the one from the spare latch and see how that goes...

[ansys]

Just as an update for those that find this thread later... I ended up fixing it by swapping out the little electric motor from one latch unit to the other. Not ideal since the small circuit board for the motor is heat-staked in place, so either need to cut wires and re-solder or cut the plastic heat-stakes and refit somehow.

The donor latch unit had a very interesting failure on the latch itself where the latch spring deeply indented itself into the plastic sidewall, preventing the latch from unlatching. I've never seen anything like it, and it was quite impressive!