Passenger door intermitant locking fault

[Trevsky]

My passenger door central locking has started to give trouble. Some times it locks ok with the central locking key fob and other times not. If the problem is the actuator is there a fix or does it have to be a new one.

[Brian H]

Hi Trevsky,

It might be worth considering the boot loom wiring as well, I am pretty certain the broken loom affects the passenger door lock.

Brian

[Robert T]

How does it sound when it does work? On mine, the actuator started to sound very sluggish before it eventually gave up the ghost and stopped working completely. The boot lid wiring loom also affects the central locking, and it is entirely plausible to have an intermittent wiring fault that could cause similar behaviour, though I would have expected that it would sound normal in this case, though I supposed a wiring fault could increase the resistance of the wire slightly and cause it to be sluggish too.

As far as remedies go, lubrication may help, but if you are taking the door card off to do this, then you might as well replace the actuator whilst you are in there.

You can also check the bootlid wiring harness where it goes from the body to the boot lid for broken wires.

Cheers R.

[Trevsky]

Don't believe it, been out for drive, central locking worked perfectly all day. Gets home amd can't even open pasenger door now from the inside???

[Robert T]

Two explanations for why the door won't unlock from inside. 1) The door is still deadlocked from locking it with the remote. Both inside and outside door handles will not be able to open the door. 2) Sticking doors is a relatively common fault. Pushing the door inwards (from outside) whilst lifting the handle can release it. Usually just needs some lubrication.

Cheers R.

[Zedbedee]

I had a similar problem some time ago. Picked up a new (to me!) actuator on ebay very cheaply and dismantled the door. There is a very good post somewhere on this site which is well worth following when stripping out the door.
Anyway when I removed the old actuator I checked it out and with a clean and a squirt of silicone lubricant it was fine and has been ever since. Gave my 'new' actuator to a friend eventually.
Don't be afraid of stripping out the door, just allow plenty of time.

[stupot50]

Going to be stripping my drivers side door this weekend, locks with the key but not the remote

[Trevsky]

I'm pretty sure the the door is deadlocked so I can't open from inside or outside. I have managed to remove the door card with the door shut but how can I open the door to get to the bolts holding the actuator in place. I have had a feel around the actuator but can't find anything to pull or push to unlock the door. Any ideas? Thanks.

[Robert T]

The diagram below shows the door lock:


Door lock front - BMW parts catalog

The actuator is just a solenoid that moves the lock/unlock mechanism of the door lock. It may be possible to squeeze a screwdriver between the lock and actuator to operate the lock, simulating what a key would do if the passenger side actually had a keyhole. Alternatively, if you can get the connector off the actuator, it may be possible to apply a voltage directly to it in order to get it to operate, possibly giving it a little mechanical assistance with your third hand.

Cheers R.

[Trevsky]

At last I have been able to open the passenger door!!! I was getting a bit worried about it because the MOT has now run out and I believe it's a fail if the doors won't open.
I managed to open the door by fiddling around with the lock plunger rod from inside the door when suddenly it clicked and I was able to open the door using the inside handle - Eurika!
I tried the remote locking on the key fob hoping it was fixed but this still doesn't work on the passenger's side.
If I remotely lock the car and then wait a few seconds and open the passenger door the alarm goes off, which I can then turn off by pressing the unlock button on the fob.
This is leading me to believe that the problem is the actuator, would you agree?

[Robert T]

Well done on getting the door open. I am still not sure you can tell whether you have a wiring fault or an actuator fault, though from experiences on here, I think the actuator is the more likely. You might be able to test the wiring with a multimeter or possibly apply a voltage to the actuator to operate it. The fact that the alarm works doesn't really tell us anything, other than the door switch that operates the interior light works. When mine failed I heard it struggling first before it died, which implied it was failing mechanically rather than broken wiring.

Cheers R.

[Trevsky]

Still contemplating my next move. I don't have a multimeter so I am thinking about testing the wiring using a low wattage bulb. There seems to be three wires in the diagram. Any idea which one is which? And do you know if the wiring plug can be disconnected with the actuator still in situ?
Thanks

[TitanTim]

A stab in the dark, but if it was the boot loom wiring the chances are once the wires fracture they will short and blow a fuse. My central locking gace up the ghost a few days ago and the 5amp central locking fuse has blown and keeps blowing when replaced which might suggest this. If its just the one door giving problems then likely its isolated to the door lock mechanism etc/. I could be wrong but I'm guessing the boot loom wiring only feeds the boot lock/brake light/bootlight? so once the wiring breaks it stuffs up all the central locking by blowing the fuse.

Tim.

[Robert T]

I'm just having a look at the wiring diagram for the car, but sadly it doesn't seem give the wiring colour codes for any of the central locking wiring.

There appear to be 6 connections to the passenger central locking. One is a 12v supply off fuse 7, which supplies all 3 central locking actuators (4 on cars with a locking fuel flap). 3 wires go across to the driver's side actuator, and 2 of these also connect to the boot actuator - all 3 also go to the central control unit. The other two connections go directly to the central control unit. The actuator appears to contain a pair of switches that swap the direction the motor is driven in - giving lock and unlock actions.

There also appears to be an additional switch in just the drivers side door lock. There does not appear to be a corresponding switch on the passenger side - and I know on my car, there isn't a lock to attach it to!

I think the mechanism is that the switch it operated by the door lock pin - so that when you press it by hand it operates the central locking - this delivers a lock/unlock signal to the control unit. The motor drive appears to be from the three wires that go to the driver's side actuator and the two that go to the boot, so all the lock motors will receive the same supply for the same length of time when they operate. This tells me that a short in any of these three would stop all the central locking actuators from working, but a clean break would stop either all three, just the drivers side, just passenger and boot, just passenger, or just boot. The supply does not directly drive the motor, so I wouldn't advise my earlier suggestion of trying to apply a voltage to it to test it - it may very well not be 12V.

There is a link to the download page for the circuit diagrams in the knowledgebase - BMW call them the ETM (Electrical Troubleshooting Manual).

Cheers R.

[Brian H]

Below are the diagrams from the ETM, you can see and as Robert has explained it is not a simple circuit to test

[Trevsky]

Thanks for the info. Based on that I might be as well changing the actuator/solenoid on the basis that this is the usual problem rather than risk damaging anything by poking around in the wiring!
I wondered if the wiring connector block was disconnectable from the soleniod without stripping it out, I'll give it a try. That way I could try connecting it to the new solenoid to see if works before changing it.

[Jonco]

Have had similar problem refer to
viewtopic.php?f=3&t=33103
and advice from Aceman.
It is a weird circuit our problem was with passenger door but the fault was in the boot. The fuses did not blow but the battery drained very quickly.

BrianH beat me to it with his copy of the diagram but the Haynes 3 series manual has a `typical ' with colour codes that is good enough to use. just ignore rear door connections.

[Robert T]

Thanks Brian. The version of the ETM I was looking at didn't have the wiring colours on it - yours looks much more helpful.

I would have thought you could unplug the old actuator and test a new one without actually removing it from the car - for most things you tend to have to disconnect them first before working on them - I'm sure someone who has changed one themselves will confirm. If it doesn't, then I don't suppose it is much more work to remove it, especially when compared to the time taken to remove the door card.

Cheers R.

[t-tony]

Slightly different problem with my n/s central locking. Will not lock with fob,I need to push button down manually but always opens from fob? My Z is 2000 2.0 Auto. Had door card off and tried to lubricate the locking mechanism,to no avail as yet,actuator obviously working to unlock maybe it just won't lock. Any help appreciated,thanks Tony.

[Brian H]

Slightly different problem with my n/s central locking. Will not lock with fob,I need to push button down manually but always opens from fob? My Z is 2000 2.0 Auto. Had door card off and tried to lubricate the locking mechanism,to no avail as yet,actuator obviously working to unlock maybe it just won't lock. Any help appreciated,thanks Tony.

My initial thoughts would be to look at the boot wiring loom, the loom once faulty can cause all sorts of peculiar symptoms.

[t-tony]

Cheers Brian,will check it out,thanks.

[Jonco]

My initial thoughts would be to look at the boot wiring loom, the loom once faulty can cause all sorts of peculiar symptoms.

Agree totally - had all sorts of permutations with ours working then not. Penny then dropped that opening and closing the boot either `cured' or `caused' problem. Check the loom where it leaves body and enters boot lid. The fix is covered in other threads and is straightforward but note that there are two brown wires ( one to boot lock - the other to central brake light ) - other wires are individually colour coded.

[TitanTim]

As Brian suggested check boot loom but if it's just the central locking on one door and it works on other door and boot it may point to the central locking solenoid actuator giving up. If the boot loom fails it tends to blow the fuses which it did on mine meaning I lost all central locking.

Tim.

[t-tony]

Can't see any damage to the loom,see that type of problem quite often at work on VAG cars. The solenoid on the n/s door is making a noise when trying to lock the door and as I've said it unlocks no problem so I am leaning towards the actuator being the culprit. Door card easy enough to remove but the door lock/catch assembly looks to be a bit more involved. Does anyone know how the lower window channel comes out,I took the screw out at the bottom of the door but this didn't really loosen the window channel.

[bowei001]

Go to the Z3 knowledge base and do a search for "central locking door actuator replacement" by Stu (July 2008). It is an excellent illustrated guide on how to remove the actuator and covers the window rear guide. I had to remove our passenger's actuator a couple of weeks ago as there was an intermittent fault (sometimes it locked/unlocked & sometimes it didn't and it was totally random). In the end I flooded the actuator using a spray contact cleaner which seems to have washed out some accumulated muck which was stopping it from working. Much cheaper than a new actuator and worth a shot. Putting the guide back was a bit fiddly as you can't get your head in the door far enough to see round the corner easily.

[t-tony]

Yes I know what you mean re. seeing into the door. I will try what you recommend as it makes sense to me. I'm not too stressed to get it done as I have my Touareg to get to work. Z3 is being taxed and insured for 6 months through the summer,well assuming we get one this year.

[Trevsky]

I have just removed the actuator on mine this afternoon. I think you are missing the bolt hidden behind the triangular shaped rubber at the top of the door. Peel this back and you will find the bolt. Undoing this frees the window channel.