If the bottom doors unlock but the top hatch stays locked remove the paneling from inside the vehicle on the back doors. check through the wire near where the hatch meets the frame at the top of the van. Its likely that the wires have been cut through do to bending.
Replace the door lock actuator/solenoid. They get destroyed with moisture or burned out if someone's leg leans on them for a long period.
... Child safety lock???
On a 1993 GMC Sierra X-Cab, the door lock relay is located on the outside of the door. After taking off the side panels, the actuator should be visible.
It depends, some are in the door, some are in a fuse box.
red and black is green and blue.
left rear quarter panel
Did you check the door latch/lock. The latch part might be broken on the inside. If you have the door already open it is easy to chisel out the old door latch inside of the door.
In the trunk on the left side - Really
w What you do is open the door in pull the lock down.the lock is located right where the door close on the side where you open the door on the left hand side.
I think so Specks42: yes they do :)
If it came equipped with power locks, it's possible the lock actuators seized up and it's impossible to lock/unlock them depending on which they were before they seized. My drivers rear door lock actuator seized up in my '92 Tempo GL and it was impossible to unlock, I had to remove the door panel with the door closed and just cut off the actuator stem (the part that actually makes the door lock/unlock) and then it's possible to lock/unlock the door.
Either a dying battery in the key fob or an electrical problem in the vehicle. Either way, taking it to the dealer is your best bet.