2008 grand prix won't lock!

Asked by May 29, 2014 at 08:42 PM about the 2008 Pontiac Grand Prix Base

Question type: Maintenance & Repair

My 2008 Pontiac grand prix won't lock.  The key fob won't lock the car and the switch on both driver and passenger side doors won't lock the car.  Whenever I try to lock it I hear a clicking noise coming from my dash. Also, when trying to lock my car the alarm will activate but the doors wont lock.  Occasionally if I'm really lucky it will work but 90% of the time my car won't lock. All of the switches unlock the car just fine.  I've already taken it do the dealership and they couldn't find anything wrong.  I don't have much money to fix it. Please help and tell me what's wrong with it?!

9 Answers

9,365

If the dealer did not check your remote,could be as simple as reprogram your remote or replace it.Other words faulty remote.

2 out of 2 people think this is helpful.
315

Do you know if your car has an aftermarket security system? Or just the factory alarm? In other words, when you set the alarm, do you hear a chirp from a siren or a honk from the horn?

1 out of 1 people think this is helpful.
15,645

This just happened this winter on my car and I didn't worry because it was only a tiny inconvenience and too cold to play around with. 1/...with all doors closed could lock and unlock with fob or key from outside the car....2/..sitting in the car with all doors closed I could lock and unlock using door switch.....3/... but I was in the habit of opening the driver door and hitting door switch to lock the doors as I got out and that stopped working..... I had electric locks working with key or fob or door switch except for that one method; so it couldn't be a fuse - right( besides there was nothing else not working.) Turns out that even though the electric locks worked in all ways but that one way,and I had dash lights,power windows,map lights,etc.,etc., all working. I found a blown fuse in the trunk . replaced it & thought can't be. It was,back to hitting the door switch as I exit. It's been two weeks and I haven't yet opened the owner's manual to see what else is on that circuit . ..... so check fuses - mine had two fuses to the electric locks..

2 out of 2 people think this is helpful.
60

I have a 2007 Grand Prix with exactly the same symptoms. When it is acting up, all 4 locks will no longer activate with the remote fob, either door switch, or by putting the car in gear. When I try to lock the doors, I do hear a clicking under the dash on the driver's side. The problem is worse when it is warm or hot outside. The un-lock function always works correctly. At first, I was going to replace the lock relay but discovered that there is not one. What I think is that there is a relay but it is soldered to the control module that is under the left side of the dash. My current theory is that it is simply a bad solder joint on that module somewhere between the lock relay and the connector to the body harness. I am currently looking for a schematic of the system to confirm my ideas.

4 out of 4 people think this is helpful.
30

Door locks some time work

3 out of 3 people think this is helpful.
60

Update: I pulled the body control module out to identify the door lock relay and to inspect for bad solder joints. No bad solder joints were found. The relay was a semi custom dual unit. (I was able to find replacements.) Anyway, when I put the module back, I connected and disconnected a few times to clean the contacts. That appears to have solved the problem because I have been a year now with no issues.

2 out of 2 people think this is helpful.
315

Thanks for the update autoX4me . So the relay "pack" is on the back of of the bcm, and you replaced it?

1 out of 1 people think this is helpful.
315

Thanks for the update autoX4me . So the relay "pack" is on the back of of the bcm, and you replaced it?

I was having a problem with my 04 grand prix locks not working. Only one would work, one of others would move up or down a little when I pressed the button, the other 2 wouldn't move at all. I took the 3 actuators that didn't work out because I was going to replace them. Before I spent a lot of money on new actuators, I figured I would by a can of electrical cleaner and see if I got lucky. I sprayed a lot of the cleaner into holes in the actuator. I plugged each one back in to test it and now they all work. One of them is week so I have to press the button twice to lock it but it is better than spending a bunch of money on a new one. Its definitely worth a try

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