Thread: 2008 Grand Prix Door Lock Problem

I have an issue with the door locks. The FOB will unlock the doors, but not lock them. In addition the switch on the driver’s side door will unlock the doors but not lock them. When the car is put into Drive the doors will not lock (although the setting is set to lock), but when shifted to Park they will unlock (if I manually lock the doors first). Everything else on the FOB works, trunk, panic. This was an intermittent problem but now it is here to stay. I have unplugged the battery, changed the FOB battery and gone through all of the various lock settings, changed them, changed them back… to no avail. Any suggestions on how to fix this?

All four doors? I don't think all four would have that issue happen at the same time...

I don't think its your FOB at all. I'm guessing all of the locking mechanisms that you've tried are tied to the same input (the FOB receiver, the driver side switch and the contact switch in the shifting mechanism) where that inputs goes to be processed sounds like the cause of the problem to me.

Any idea where the input goes and what I may need to replace. The door lock fuse is good (as the doors will unlock). I don't have a manual so I don't know where the relay is (if there is one). I took the bottom half of the dash off on the drivers side and could not find anything that looked like a relay. The local dealer won't give me any input, they say bring it in and we will take a look (and your money)...

I believe all of the inputs feed the BCM (body control module) one way or another. I dont think it would be the driver side switch only either but who knows.

Originally Posted by GeeXPee

I believe all of the inputs feed the BCM (body control module) one way or another. I dont think it would be the driver side switch only either but who knows.

I would look at the door switch, its the master cir if its shorting out it may not be completing the cir.. this is where I would start..

I have a 2004 Grand Prix but I have been having the exact same problem. I took mine into the dealership today and they said it is a computer module that is causing the problem and it would need to be replaced.

Did the dealer give you a quote on what it will cost to replace the computer mod? The funny thing is just after I posted the original problem I had a buddy do a scan and there were no issues found. After the scan the locks worked fine for the last week and just yesterday Sybil's (my name for the car) locks were back to the same old problem. I pulled the FOB's apart and the battery clips were broken on both (again... I fixed them last week by re-soldering the connection). Not sure if the FOB's have anything to do with the problem when they are not making good contact with the battery...

I am starting to have the same issue with the 08 I have. Did you track this down to the BCM? I am trying to confirm this before I buy a new one.

I am having door lock problem, but in a different manner. The key FOB and the key will lock the door but will not unlock in. The key FOB only unlock the trunk. I need to get this fixed fast as i have left my car unlock for a while now and I am afraid of someone breaking into my car. Thanks

Or just push the drivers door lock button. Once to lock delayed style. Twice to set the alarm.


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