I have a 2000 B3500 and the double side door is locking when it's closed. Also the front two door locks no longer operate with the switch on the door or with the remote. Any ideas as to what the issue might be? The front two doors failed first, and the auto locking of the side door just started.

 

What happens when you try and unlock the doors from the switch on one of the front doors?

 

Nothing happens now. When I first got the car the switch on the door would lock and unlock all the doors. After a few months the front doors stopped working. Now the switch does nothing, but when I close the side door it locks as soon as it is closed.

 

Sounds like some wires are broken/shorted...... That is going to be a fun one to find.... Wiring diagrams are going to be a requirement. Do you have the Factory service manual for it? If you don't, you are going to need one. Likely can pick one up cheap (relatively) from Ebay, or a few other places. The digital version is usually less than 30 bucks.