Power door lock not working properly?

2008 CHEVROLET COBALT

89,000 MILES • 2.2L • 4 CYL • 2WD • AUTOMATIC

L8NDAD

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When I push either the drivers door or passenger door power door lock switch to unlock the car doors nothing happens. But when I push the "Lock" side of the switch, all the doors unlock. Sometimes if I push it over and over, they will lock and immediately unlock again. This is only when I push the buttons. They don't do anything when driving. I have heard some people say they lock unlock while driving. Mine just wont lock. I replaced drivers door switch and still same thing.

Jun 1, 2015 at 10:58 PM

KASEKENNY

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If both doors are doing the same thing then this is the body controller (BCM) that has failed.

I attached the wiring diagram if you want to prove it out. You want to check voltage at the BCM coming from the switch and then going to the actuator. I suspect the voltage will not be correct coming out of the BCM.

I attached the wiring diagram for your review and here is a guide that will help with doing this type of testing:

https://www.2carpros.com/articles/how-to-check-wiring

Also, here is the process on how to replace the BCM if I am correct. Also, how to program the replacement BCM.

Let us know if you have questions. Thanks

Images (Click to enlarge)

Dec 4, 2020 at 2:32 PM