I have a 2003 PT LImited. The door locks intermittantly lock-unlock lock-ulock, lock-unlock several times regardless of speed, it happens while idling, driving forward, and backing up. About a year ago the spark plugs had to be changed and the problem stopped briefly. It is now happening again. Can you please tell me what I should look to in order to fix it?

go to chevy dealer
this is a dangerous car, take , Ralf Nader with you.
author of old book Unsafe at any speed..

chevy should hid their head in shame. for such danger
bad programming for sure.
they may have a recall fix for free, seems it should to me.

Steve, I'm AL the owner of Big As Auto Repair.

When a door lock is active intermittently it can be a couple of things. (1) The door lock actuator can be a the point of going bad.(2) The Key Fob unlock button can be bad and you have to press it several time to work OR if it is unlocking the door by itself at time a sticking button can cause this issue as well. Hope this helps and have an awesome day. If you like visit my auto repair website here: http://www.bigasautorepair.com/

With factory controls the door locks get there signal from the body control module and can be set to lock every time the car gets above 15 mph if a door jam switch has a intermittent connection failure this could cause the door locks to cycle at will.
With a aftermarket alarm most lock and unlock with the key cycle and loose grounds can make these modules cycle the locks at will also.

No, not so strange. - Happens a LOT. Sometimes you can get them working again by cleaning the electrical contacts that are on the front edge of the door and their mating contacts on the "B" pillar area. If cleaning the contacts does not get them working again, then you most likely need to replace the door lock actuators inside the doors.

Possible issue with the remote controller unit - main board or sub assemblies. The intermittent behavior seems to indicate that the board is erratic to detect at the same time the individual locks work at times.
So make sure all the connectors to the door and to the main board controller are tight. You can remove the main unit and check for any loose connections or clogging, specially water in all the door units or in main unit. If so dry and test.
Otherwise the main unit is a suspect.

fast blinking lights are a sign of a burned out light bulb. Door lock actuators wear out. Since all the actuators operate every time you lock or unlock the doors, it's not unusual for multiple actuators to go bad

The door lock switch on door panel has water in it.

I am looking for the same problem. The power door lock work only on to unlock. When I try to lock the doors I hear only a cliking three time but the doors doesn't unlock

does it happen at miscellaneous times, or is it at specific times, i.e., when you hit a certain speed, etc? If it's intermittent, then you may need to replace or clean the switch for the door locks. If it's at a certain speed, then most Chevrolet cars and trucks past about 1998 or so will have an automatic locking device that keeps kids from escaping while the car's in motion. They can be programmed to actuate at different times, so you may want to look at your owner's manual to see how to set yours, if you feel that it could be this.

this somthing that happen to me try holding your key remote next to your sub push unlock and lock at same time for 10 seconds then try it?