Some information on the BMW E46 Door Lock Actuators
One problem that I heard now and then is, I found my car unlocked with the windows and sunroof wide open. I know the windows were shut and the doors locked when I left it. Since I started this web site I've only heard this story a small handful of times. So far there has been no definitive solution, but, I believe it's the Driver's Door Lock Actuator assembly that is causing the problem. As you may already know you can open all the windows on your car by pressing and holding the unlock button on the key fob for > 3 seconds and the windows will start going down and the sunroof will open. This function can also be activated via the key in the driver's door and rotate the key CCW or counter clock wise (left hand drive cars only) and hold for > 3 seconds. At first I thought maybe the problem was a damaged windshield lower cowl cover allowing water to drip down and seep into the passenger compartment above the GM5 module. I thought that this moisture might cause the GM5 to falsely detect a key in the door turned CCW situation. So whenever I hear about this I always ask if it happened during or after a good rain. It was sometimes yes and sometimes no. This lead to another theory, the door lock actuator assembly was bad and falsely sending a, key in the door turned CCW, signal. After all this is just one signal and it is detected via a single hall effect device. Ok, so what can you do if you are having this problem? Well you could just replace the door lock actuator assembly or try pulling one wire. The signal is ERFT or Unlocking, Driver's Door. It is connected to pin 6 on the door lock actuator or pin 20 on connector X253 on the GM5 module.
Another common problem with the actuator is when the key in the door just spins with no resistance. There is a linkage between the key and the actuator that breaks and falls out. This might happen when the lock is forced or it may just get old and break, I don't know for sure. Anyway if this happens to you, you might need to replace item number 11 in the drawing below. This is called the Catch with key and can only be obtained from the dealer. You will need to provide your VIN, driver's license and vehicle title when ordering. To get the unit out you don't need to take the door apart. All you need is a 4mm allen wrench. On the side of the door there is a plug. Remove the plug, insert the allen wrench, loosen the screw (about 10 turns) and the lock cylinder should pull out. See my detailed procedure here door lock cylinder replacment.
On the M3forum.net forum, user FCars4Ever created a how-to for replacing the
door lock actuator.
Here is a link to his post. http://www.m3forum.net/m3forum/showthread.php?t=242785
Here is another one from someone else. http://www.tuningemotion.com/forum/showthread.php?p=49481#post49481
GM5 Repair Service web page.
To V23078-C1002-A303 web page.
To V23072-C1061-A303 web page.
BMW General Module III (GM3) Page