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Discussion Starter #1
Im trying to figure out why my doors wont unlock when put my car in park and shut it off. I think it use to but never really noticed it till now. cause now i have to hit the unlock button to get out where before i didnt have to. anyone able to give me an Idea. the latches work and the handles are fine.
 

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Have you had any trouble with getting the key out of the ignition as well? If so I would say it may be related the shift linkage and the car not thinking its fully in park. I had that problem a couple times after I had my trans serviced. Had to take it back and have the linkage adjusted. It also sounds like it could be something electrical. I would think it was a bad relay or fuse but if the unlock button still works then that may not be the case. I would have to look at a wiring diagram to see what is suppose to trigger the locks when putting the car into park
 

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But there is a "PNP"(Park Neutral Position sensor) switch mounted on the transmission that signals to the BCM if it's in Park or Neutral.
 

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Ah yes that sounds right. I bet there is something up with that sensor. I knew there had to be something that took a trans signal and told the BCM to unlock the doors
 

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What year Cobalt or G5?
 

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Before buying a new switch make sure this is your problem. You might just have a broken wire or dirty contact. GM part number for 2008 2LT is 24219476, there again verify with VIN to make sure.
 

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Discussion Starter #10
I reset the car by disconnecting the battery, Its working now but question i have now is. is it only suppose to unlock the drivers door or the whole car???
 

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The whole car I believe.
 

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Whole car
 

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Is it the Park Neutral Safety switch not triggering? Could be the solenoid not engaging.
 

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or could also be parking paw too...I was referring to the switch, it should be either a relay or solenoid from the TCM. Are you getting a DTC or CEL? (Diagnostic Trouble Code or Check Engine Light)

Sorry im a bit late on that, the switch should automatically unlock all doors.
 

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Next time it happens, disconnect battery and re-seat "P1" and "P2" on "BCM" module. I forget which one carries the gmlan from "TCM". It won't hurt to re-seat them both. Probably a buildup of corrosion.
 

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Discussion Starter #18 (Edited)
Im not getting a check engine light I havent plugged in my tool to scan for codes. coby you got a diagram on where i can find the P1 P2 BCM? BUT would all doors unlock if theres no passenger in the front seat or would only the one drivers door?
 

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Here circled in red is "P1" and "P2" is the similar connector to the left.

 

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Discussion Starter #20
But the question I also have is would the door unlock work on all doors if there isnt a passenger in the vehicle.
 
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