2008 Grand Prix Door lock actuator failure


New member
I bought a 2008 Grand Prix (110k odometer) for my grandson and I'm in the process of clearing up minor mechanical issues. I bought it from an individual and didn't notice that all four doors have locking/unlocking issues (manual & remote). I noticed that some of the doors would lock/unlock some of the time but not one of them worked every time. Most of the time they moved a little but not enough to lock/unlock.
I bought two new remotes on eBay for $18 and carried them to the Chevrolet dealer to have the programmed ($45 for both). While I was there and thinking there might be something wrong with the BCM, I had the service dept check out the door locks. They advised me that all four locks were defective. I was still afraid to buy them all, so I bought only one for the left rear door to install myself. After installation it worked perfect. I ordered the remaining locks online at GM Parts Headquarters and saved almost $200.
Unlike older vehicles with separate actuators, this model has actuators built into the lock itself as one assembly with a 6 pin connector (only five pins used). I had already looked up the connector and found 12v was applied on pins 2 & 3 (Pin 1 not used) to lock and reverse the polarity to unlock. There were screws that hold the cover on the assembly but there was a metal back-plate with two rivets that kept me from taking it apart. I was surprised when I drilled out the rivets from the backside (not the striker plate side) and discovered a small motor with a worm gear drive. By the way, The back-plate can be reinstalled by drilling the shouldered rivet post and tapping for an 8-32 screw. The mechanism was free and worked smoothly so the problem has to be loss of power in the small motor. The motor actually run without a load when I applied 12v to it. The motor body is about 1 1/4" long and 3/4" elliptically shaped.
My question is, has anybody had this much trouble with the door locks on Grand Prix's? Also, does anyone know if there is a replacement motor on the market that will fit these locks. There are several styles of actuator motors for sale on eBay for about $6 but none of them are identical to mine.
It wont help me much this time around but there must be a lot of people out there that don't have $500 to spend on parts alone when they can be repaired for less than $10 each.



What did you end up doing? I have this same issue with my 08. I thought it might be the BCM as well.