Models:
This applies to all E32s and even the E34. There seem to be 2 types of microswitches. The newer one has shorter pins. I assume this is a design improvement. The newer one I got was from an '89 model.
Background:
The central locking system is activated by a microswitch unit with 3 switches in it. For those of you who want to know it all here is a state diagram (supplied by Jon Evans) for the lock:
| State | A | B | C |
| Unlock | x | 1 | x |
| "off" | 1 | x | x |
| Lock | 1 | x | 1 |
| Deadlock | 1 | 1 | 1 |
Fixing it: There are 2 ways of replacing the microswitch. One involves getting the entire lock assembly out. The second is more of a quick fix for the more experianced tinkerers among us.
As one can image removing the doorpanel might help...since most of you have done this a multitude of times I'll just give a quick rundown :)
Pull off the wood trims. This will uncover two screws near the doorhandle. Undo these. Then start pulling at the bottom part of the panel so the clips that hold the panel come out. Then start pulling at the top of the panel so that the clips over there also pop loose. Now you should be able to pull the doorpanel upwards. Now it's time to remove the connector that goes to the mirror switch and the courtesy lights. It might be helpful to have someone hold the panel while you undo the electrical connectors. Now it's time to remove the bowden cable that goes to the door handle. If you pull the cable slightly backwards it'll pop out of the guide in the doorhandle. Now you can unclip it from the doorhandle.
Remove the two mechanical rods that go to the servo and the lock. Remove the servo aswell.
To remove the lock first push the slider towards the front of the car. This will allow the doorhandle surround on the outside to fold off.
After taking off the doorhandle surround a philipshead screw and a ring around the lockcylinder are uncovered. Remove these. Now the doorlock should be loose so you can take it out. There is not much room so this could take some patience.
Now it's time to replace the microswitch. Remove the plate connecting the servobracket to the lock cylinder.
Clip the tiewrap that holds the wire to the microswitch. Remove the Black and yellow connectors from the bracket. The bracket has two locking points on the rearside of the connectors. Now remove the clip that holds the microswitch housing to the lockassembly.
Now you can pull out the old microswitch and install the new one.
And as always replacing is reverse of removal :)
Before putting the doorpanel back on check that the servo is positioned properly. If it's to far to one side the door can't be opened from the inside door handle, if it's to far to the otherside the door won't unlock.
By using the "quickfix" way. You can leave the lock in the car. First remove the coveringplate (only remove 1 screw from the servo). Then remove the tiewrap and the connectors on the microswitch wiring. Pull the clip on the microswitch housing off. Remove the housing of the microswitch. This is kind of hard since the window guide is in the way. But it can be done !!
Story by Johan735.
If you would like to add any comments, remarks and/or corrections to this procedure, feel free to email Mike Oswald and we'll put it on our site. Share your experiences with us so others may benefit from it.