Haven't posted in quite awhile, but have a current issue that is baffling me. My Panel is a 2009 with under 41K miles. The door locks have been acting up. Today is the second time that this has happened. I start the car, set into gear and the door locks, lock as they are supposed to. But, once driving, they will unlock and I hear clicking from maybe a relay, trying to lock again. If I hit the lock button, they will lock, but once again, unlock. When I stop and turn off the engine I hear the clicking again. Try to lock the doors from outside with the key fob, the doors lock and immediately unlock. Manually lock the driver's door with the key and the lock will unlock after locking. I can hear the clicking as if a relay is trying to latch and lock the doors,. Eventually, this issue seems to right itself and stops acting up. Anyone have experience with this issue? Is there a relay that can be replaced, or a fuse removed for this circuit or is the locking protocol part of a computer module? Don't know with prolonged clicking whether the battery will suffer while parked. Any suggestions would be appreciated. I did have the three volume repair manual, but sold some years ago. Seems like a computer glitch to me.

 

 

I would look at the Park/Neutral sensor on the transmission.

 

Thanks for the fast reply. The battery is only two years old, AC Delco. Great batteries. Never had an issue with the original that I replaced after 7 years. I will try the reboot. A friend of mine thinks that one of the door lock buttons is shorting out. Not sure if the switches will pull out from the outside to investigate vs opening up the door panels. If I had the manual, I would be able to look at a schematic to check out the wiring circuit. The saga continues.

Thnaks, donbrew. I thought about that sensor as well. Will try to eliminate the possibilities.

 

Most any auto parts store will load test your battery, for free. Post up the numbers from the test here. Many times they will think the battery is good, when it is not.

 

Age of battery is of no consequence.

Each door lock is controlled by the BCM, so not that.

BTW, the panel rear access doors have a connection to the Instrument Panel. The IPC gets a signal from the BCM, then it activates the relay under the hood on the strut tower which sends B+ to the door lock. The BCM supplies ground to the door lock.

I'm not sure where the BCM gets the signat to lock the doors either the PNP or the shift micro-switch.

 

Thanks for the schematic. Very helpful. I'm testing a possible cause with regards to the key fob. I just placed my finger over the unlock icon without depressing and all the doors unlocked. Didn't need to double click. I had issues with the fob not making contact so I did the aluminum foil trick and got the fob working again for all the buttons. Might be possible the foil has become loose over time and is making contact under the unlock button. Once again, there is nothing wrong with the battery. This intermittent issue has only happened twice. A low or marginal battery would be causing other issues all the time. Thanks for the replies.

 

Not the key fob. Doors stayed locked for hours and then in the morning, I found the doors unlocked. They will lock, but at some point, will unlock. Back to square one. Very strange that they will stay locked for hours and then unlock themselves.

 

Did you try the battery disconnect (lobotomy) ? It's free and worth a try because it will reboot the car's system.

 

I will once the temps warm up a bit. That's next on the list. Thanks.