Central Locking Problem

[S2_By_Proxy]

Hello All,

My Father has an S2 coupe (B3 engine). He bought the car new and it has been pretty much trouble free. However, recently the central locking has started to play up. He has asked me to investigate the problem for him. Any chance of some advice/assistance?

When locking the car from the driver's side (uk, right) with the key, the central locking activates on all locks except the passenger door. However, if you then lock the passenger door manually, operating the central locking to open the car from the driver's side unlocks the passenger door as normal. The central locking operates normally (locking/unlocking) if operated from the passenger side.

I have removed both door cards to investigate and done the obvious things, wd-40, fuse, checked wiring, to no avail. Nothing appears to be loose or out of place. Has anyone experienced this problem before?

Many thanks, Ed.

[Phillio]

sounds like the door lock actuator? (small blue thing in bottom of door) might be playing up. check the vacuum line going to it and that it is not jammed when locking/unlocking. does it feel stiff when locking with key from passenger side?

when locking with key from passenger side this is forced down mecanically, only called into action when locking from drivers side.

When i got my coupe, Central locking only worked when using the passenger side, had to route a new wire from the pump to the actuator to trigger it to lock the other doors/fuel cap/boot. it is unlikly to be electrical on yours as it is only one lock that doesn't work.

Cheers

Phil

[RoscoS2]

Had troubles with mine a few weeks ago, thought it was down to the heat playing with the electrics. I had to drive the car with the doors locked at one point or the alarm would go off!!

Ended up leaving the car open and disconnecting the battery then, connecting again, this seemed to solve my problem. Not sure whether it will do yours.

Do you have remote locking or just central?

Rosco

[S2_By_Proxy]

Thanks for the response. I do have a little experience with vacuum c/locking from playing around with MBs. It was my immediate thought that the problem was vacuum orientated, however after inspection I figured that it could not be so because the passenger door still unlocks fine. My understanding is that the vacuum sucks the door lock down and uses pressure to blow/open the lock. If there was a leak the door would not unlock via the c/locking pump? Is this logic correct?The door lock is not 'stiff', as you suggest Phil. When you say you had to route a new wire, do you mean you replaced the vacuum hose all the way from the actuator back to the pump?

I should have mentioned this Rosco, but I did not want to over complicate my original post. Yes, the car does have remote c/locking. However, bizarrely, the alarm/immobiliser is after-market not Audi and fitted by a third party for the dealer before sale. The wire to the actuator on the driver's side has been spliced. Also, the remote locking does not appear to be working. The alarm remote seems to do nothing. It has batteries but the alarm is not activated and the car does not lock. I think my technophobic Father has just given up on it. I'll try disconnecting and reconnecting the battery to see if this has any influence on the problem.

Does any of this elaboration suggest anything else?

[Phillio]

the vacuum sucks the door lock down, this is correct. you're right that a leak would imply that it would not lock either, the only thing i could think of is that it needs more pressure to unlock or something.

If the vacuum pump is running when unlocking (you can hear it, next to the back seat, drivers side) then it means that either the vacuum line to the actuator is dodgy or the actuator itself is faulty. I would take it out the door and then try locking/unlocking a few times to see if there is any vacuum being generated. (the vacuum line unplugs pretty easily from actuator)

The signal to lock/unlock the door is generated by a electrical contact in the actuator (from turning the key) which in turn triggers the pump. once the pump is running then it is just on air pressure, not elec anymore. The remote should trigger the pump in the same way. this is the wire that i had to replace in mine, electrical, thankfully not the vacuum. there is a t-piece for that in the loom somewhere that i wouldn't fancy finding!