Central locking, please diagnose this...

[TDE30]

Alright, yesterday I replace my driver's door lock actuator with a brand new one from BMA, and I seem to be having similar situation before and after the fact. Since I am an electrical newb and know very little about the central locking in my E30 I will describe the situation door-by-door.

Driver's door: When I lock it, the driver's door will lock, all other doors lock but immeadiately unlock and I hear a grinding/buzzing noise from the driver's rear door. A friend and I think it may just be in need of a new lock cylinder, as it is unable to single lock (only double lock). It is also very difficult to turn the key. I am going to try some lock lube this evening and see if it is any easier to turn.

Passenger's door: When I try to lock it, all door lock and then immeadiately unlock.

Driver's rear door: Locks/unlocks normally but I hear the aforementioned grinding/buzzing noise.

Passenger's rear door: Locks/unlocks normally.

Trunk: When I lock it, all doors immeadiately unlock.

Fuel door: Locks/unlocks normally.

From what I gather, it is one or more of the following:

Driver's rear door lock actuator
Central locking control unit
Driver's door lock cylinder
Some other electrical custerfuck
Possibly a bent rod/arm in one or more doors

I located a VERY helpful piece of information regarding the central locking system and how it works, refer to below link.

http://www.mesaperformance.com/faqs/centlock.html

ANY help is very much appreciated, I have been trying to diagnose the grinding noise issue and the immeadiate unlocking issue for a while now.

Thanks.

[thereisnoyun]

Its probably door open and close sensor that engage the lights. The one in the jam, that your door close on. If that is not making contact and not engaging correctly, the central locking module will think the door is open and will kick into safety mode and unlock right after you try to lock it. Its the fail safety for the driver side.

Second possiblity is something is catching/ usually fabric is catching on the rod that moves the cylinder. somethign is too taught around the level and its holding it from travel freely. The sound you hear, the grinding sound is from the locking actuator motor trying to move the lever.

But I'm almost certain is the first thing I mentioned.

[TDE30]

Any possibility it could be the lock actuator on the driver's rear door (the door making the grinding noise)?

Whereabouts is that door open/close sensor located?

[87e30]

Any possibility it could be the lock actuator on the driver's rear door (the door making the grinding noise)?

Whereabouts is that door open/close sensor located?

I know on my coupe there is a little rubber thing that is in the door jam. It's right by the hinge that the door opens on. Basically it just pops in and out when the door closes.

[TDE30]

Ah, that part. Yeah I actually have two of those from the dealer. The only reason I don't think that is it is because the interior light turns on and off according to the door's position. It works fine, so I think that door open/close switch is functioning fine.

[TDE30]

Anyone?

[Dragowl]

I had a similar problem with my vert although with only 2 doors and a trunk. The first thing I did was pull the driver's side door panel and test that actuator and its function. See if the actuator will still lock the doors if you manually pull/push the plunger. If the same issue persists I would think its the trunk actuator. Those are the only two from my limited knowledge that are capable of locking all doors. You can also unplug the trunk actuator to isolate the problem as well.

[OrganicMechanic]

IFixed Mine...

adjusted the one for the trunk lock under trim panel. Loosen 2 6mm screws and move slightly up and re-tighten. Fixed mine.

[TDE30]

Neither of those suggestions were the culprit, thanks anyways though.

I ended up dropping the car off at the mech before I did something stupid and irreversible, apparently one of the rods in the driver's door was bent (so replacing the actuator turned out to be pointless) and a few small round rubber seal things needed to be replaced. Roughly an hour later and all was working well, much better than before.

Thanks again for the suggestions.