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E34 BMW Door Lock Microswitch Problems

I have a 1990 BMW E34 525i. Lately it has been giving me some grief when it comes to locking and unlocking the doors. I took a closer look and I’ll let you in on what I found the root cause was.

The E34 was in storage for a year. I should note that the doors were left unlocked. I connected the battery and started it up. Everything worked great. I drove it to the house and locked the doors with the driver side door key cylinder. I went out a  few hours later to get in the car and nothing happened when I tried to unlock it.

Great. Oh E34, how do I love thee? I don’t.

After a quick search online I found the procedure to manually override the unlock function via the passenger front door. I managed to get in the vehicle. My work was about to begin.

Instead of giving all the details of what I tried and looked at, I’ll cut to the chase to save you time.

Put your ear on the door just above the key cylinder. Turn the key left and right to lock and unlock the door. You should be able to hear the microswitch click in both directions. Do this for each door. I noticed the passenger side switch did not click in the lock position.

If you do not hear any clicks, inspect the respective switch. This tip should work on any E34, BMW, or any car that has microswitch on the door key cyilnders.

I removed the right front door panel and got down to the switch. Another thing: It helps to remove the window run to get the entire handle assembly out. Be prepared to find the lower bolt on the window run rusted and impossible to remove. I had to drill it out and replace it with a nut and bolt. The threaded boss on the lower tab will knock out. Thak you BMW engineers for seeing into the future.

See the video below for an explanation of the door lock microswitch and its anatomy. You may be able to fix your switch. I had to replace mine all together.

Alas, if you own and E34 you should stay busy trying to keep up on maintenace and operability considering the age on these vehicles.

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