power locks

A friend of mine has a chevy cobalt '08. His power locks are crazy. when he clicks the lock button they unlock. when he clicks the lock button they do nothing. this problem continues with all four doors. ALso the remote control used to work but now does not anymore. I looked at it. I think it might be a bad ground. Any thoughts?
Thanks

Did your friend try to replace the batteries? If so, I’m wondering if this notice in the owners manual (p. 2-6) applies: "When replacing the battery, use care not
to touch any of the circuitry. Static from your body
transferred to these surfaces may damage the
transmitter."

Keep me posted on your progress!

Sarah
GM Customer Service

you know...thats a good point! I think he might have touched it! That would resolve the problem with the remote control! I'm still wondering though, if the buttons from the car itself don't work because of a bad ground?
thanks

The door lock act the same with both switches? You may have a problem with the bcm, this controls the door lock operation. Lock and unlock use the same ground. Unlock is run through a 15k resistor in the switch. The BCM sees this and commands unlock, if no resistor is seen, lock is commanded. It uses a 5v signal and senses the drop in voltage. The remotes can be tested, usually for free, at any GM dealer.

The door lock act the same with both switches? You may have a problem with the bcm, this controls the door lock operation. Lock and unlock use the same ground. Unlock is run through a 15k resistor in the switch. The BCM sees this and commands unlock, if no resistor is seen, lock is commanded. It uses a 5v signal and senses the drop in voltage. The remotes can be tested, usually for free, at any GM dealer.


yes. the door does the exact same thing with the driver's switch as well as the passenger's switch. How can I find out if it is a bcm problem? I was thinking a bad ground because if the ground has resistance, the bcm might think that he is trying to unlock it when he actually is locking it. And when he tries to unlock it the bcm cannot "read" it because there would be too much resistance.
thanks!

If you want to check the ground, I'm pretty sure it's under the drivers seat (floorboard). A scanner is really needed to see what the BCM is or is'nt doing. The BCM's in these have been known to cause various problems.

thanks! I appreciate it! I'll look at the ground and if that is not the problem I'll try to get a scanner and see if the bcm is ok.