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05 Grand Prix Door Lock Issue

A

acarboneau10

New member
When I unlock my car either with my key fob or with the switch on the door, the driver's side door is the only one that unlocks. When I put the car in drive the doors all lock properly, but when I put the car in park, once again only the driver side door unlocks. Additionally, if I manually unlock all of the doors, they will all lock when hitting the button or the key fob, but only the driver side unlocks... This problem just started in the last few days. I have had the car for about 6 months now and had no previous issues. Thanks for any help you all can provide!
 


OK first off what year is your car? Second of all do you own an automotive test light? Best thing to do would be to test your lock and unlock wires at the bcm and I'm pretty sure there is a wire in the passenger kick panel as well. By using a test light you will be able to test if the wiring is fine and that would tell you if it the switch.

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It could however be the bcm if the remote and switch aren't working properly. Its hard to say without testing the wires at the bcm in the drivers kick panel. FYI the bcm is the blue box looking thing closest to the fire wall all the way to the left if you're sitting in the drivers seat. By the emergency brake. Also look up a wiring diagram at Bulldogsecurity.com and that will tell you where the unlock and lock wires are. If all the wiring is working correctly then you will hear the door locks actuate when you hit the wires with the negative pulse (or ground since you'll be grounding the test light to chassis ground).

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My car is a 2005 Grand Prix GT. Thanks for your input, and it looks like either wiring or the BCM itself. I don't have the means to test the wiring myself, but I have a friend that has a test unit so I will see if we can hook it up and troubleshoot the issue. If I can isolate the problem, would you recommend a GM dealer for service on this issue.. or would any mechanic know how to fix the problem? I really appreciate your help!
 
acarboneau10 said:
My car is a 2005 Grand Prix GT. Thanks for your input, and it looks like either wiring or the BCM itself. I don't have the means to test the wiring myself, but I have a friend that has a test unit so I will see if we can hook it up and troubleshoot the issue. If I can isolate the problem, would you recommend a GM dealer for service on this issue.. or would any mechanic know how to fix the problem? I really appreciate your help!
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Your BCM would need to be programmed once it's replaced. If your mechanic is not a dealer, he'll need to have a real good relationship with one.
 
My mechanic is not a dealer, but I have no problem taking it to the local dealer to get it programmed. However, I am not having any other issues with my car, so is it common for a BCM to only have one problem like this that causes the whole unit to go bad?
 


acarboneau10 said:
My mechanic is not a dealer, but I have no problem taking it to the local dealer to get it programmed. However, I am not having any other issues with my car, so is it common for a BCM to only have one problem like this that causes the whole unit to go bad?
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Common? BCMs in our era Grand Prix aren't a common failure point, but when they do fail it's usually a single function that quits. The 2000-2003 W bodies? I sold a ton of BCMs for those cars.
 
I haven't checked the battery, would that cause a similar issue? Like I said, everything else on the car works perfectly fine other than when I unlock my car, only the driver side door unlocks. However, if I manually unlock all the doors and then hit the lock button, they all lock normally... which is why I was led to believe it was switch wiring or BCM issue.
 
Good to know its not common... My old Grand Prix had 216K and never had an issue like this. I appreciate your help though, I am not the most mechanical person... the extent of my capabilities are brakes and wheel hubs, so not very technical.
 


You didn't have a power loss problem like a battery replacement, did you? It almost sounds like your car forgot its "auto door unlock" programming. From the owners manual: This screen can be used if ON was selected for the AUTO DOOR LOCK feature. This screen allows this feature to be turned off, used for the driver's door only, or for all of the doors. This is programmed through the DIC.
 
Below Average Joe said:
even if it is a 3 button dic?
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My owners manual didn't differentiate between the three button base level DIC and the five button uplevel DIC I have in my 2005 GT. I didn't read the whole section though. I just remembered the option when I was playing with it when I first got my car. The DIC, that is... :th_laugh-lol3:
 
I have not had a power loss on the vehicle, but I will go out and mess with the DIC during my lunch break and switch the features to see if that resets or fixes anything. Next step would be a battery test?
 


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