Central Locking Mystery... Any ideas? Help?!

[PGAHopeful26]

So, my sister's E36 (my old car) has been acting up recently. When she goes to unlock the car with the key (key in door, not remote), sometimes it will refuse to let her unlock it.

Sound confusing? It is. I'll explain further. When she puts her key in the drivers door and turns it to unlock it, the door latches (across the car) unlock and you hear the audible click. However, almost immediately afterwards, the car locks all of the latches back. It will do this an unlimited amount of times, preventing her from getting in the car.

Now... if you sit and hold the key in the unlock position (fully to the right... I think) the same thing will happen, but the door that the key is in will stay unlocked while the rest of the doors will lock. If you get into the car after that, put the key in the ignition and turn... Guess what? Nothing happens. No starter, nothing.

I can only guess that the immobilizer is at fault for the lack of starting, but what in the world could trigger such symptoms? She has a 1994 325is Coupe.

Any help is greatly appreciated.

[Eric93se]

Well it's either the lock actuator or its the ZKE. Try unlocking in the passenger door, if it works fine then its the drivers door lock actuator (ebay new ~$20 aftermarket).

[PGAHopeful26]

Well it's either the lock actuator or its the ZKE. Try unlocking in the passenger door, if it works fine then its the drivers door lock actuator (ebay new ~$20 aftermarket).

Just tried the passenger side, same thing. It unlocks, then locks. I also tried holding the passenger side to unlock that door, and then start the car... same thing. No start.

What in the ZKE would cause this?

[Eric93se]

I have a funny feeling it has to do with the door sensor, forget what it's called, the one in the door striker.

[PGAHopeful26]

I saw a previous thread that mentioned that. When I looked up the striker on realoem though, it gave a part # for a striker without a sensor.

I guess the easy way to check is just take it off and see if there's anything behind it.

[PGAHopeful26]

I have a funny feeling it has to do with the door sensor, forget what it's called, the one in the door striker.

Just checked. It does have a plug in the back of it, so I would assume it has that sensor. If it's doing it on both doors... Does that mean both sensors are bad?

[Eric93se]

No it doesn't mean both are bad. One way to test it is to see if the under dash lights turn off when you push the tiny button on the striker.

I haven't had to replace mine, but they say it's tricky to replace because the wires can fall into the b-pillar, so you've been warned . A more proper way to test it is to remove it and use an ohm meter to see if the resistance is near zero like it should be.

[Eric93se]

Here's a video (in russian) the guy has the same problem and he tests his door strikers (the russian way lol). Maybe use google translate to read the comments and his personal comment in the vid description.

https://www.youtube.com/watch?v=nQqYSa4Uaf0

[PGAHopeful26]

I just ran a quick test. When the sensor button is pushed in, the windows raise up (coupe feature). When the sensor isn't, the windows drop.

I tried pressing the sensors all the way in (screwdriver holding them in) thus ensuring the car thinks the door is "closed", then trying to use the lock on the door. The same locking issue happens, no change. If the door is "open" however (not holding in the sensor button, windows dropped) turning the key allows the door to open (although just that one door).

So weird.

[flyfishvt]

ZKE is the body control module. It is pretty rare for them to fail. It is very common for one of the lock actuators to fail. If it is an actuator causing it the best way to find the source is to unplug them one by one. Start with the actuator for the trunk lid and gas filler door. Next remove the driver's door panel then do the passenger. If you unplug one and there's no change then plug it back in and move to the next one.

Something else to look at is the wire harness in the trunk lid hinge. It's a well know issue. A bare wire could be grounding out.