The door locks on my 69 supreme are giving me some trouble. I have the door panels removed so I can view the mechanism and everything appears to be fine but when I shut the doors with the locks engaged they unlock. Also when sitting in the car with the doors closed I can lock the doors no problem. I realize something is causing the lock to disengage when the door is shut but I can't see any problems. Any suggestions?

 

On some years the doors have to be locked from the outside with the key, I know the '68s are like that - don't know when it changed.

 

Thanks The lock cylinders on the doors don't actually unlock with the key I have so I have to get new ones so we'll see how that goes.

 

When the door is open and you push the lock button down, then push the door handle button in and then shut the door. '68 works that way also. My '69 GMC must lock with the key. If you remove the lock cylinders and clean the outside you will find a code on there and get keys cut at the dealers for said cylinders.

 

Its designed to do that to help prevent you from accidently locking the keys in the car. As Yellostatue stated, you can either use the key from the outside to lock the doors, or press the lock button down before you close the door, then hold the door handle thumb button in as you shut the door and the lock will remain locked.

 

Thanks that makes sense. My next question would be, how do I remove these cylinders so I can get a look at that code?

 

There should be a horseshoe clip that holds lock in from back. Slide the clip usually left or right but sometimes up or down. Lock will pull out from front. Take to a local locksmith. Dealers make enough already.
Kevin