I have a 1999 blazer with all power locks and today all the lock buttons in the truck stopped working, the doors and the hatch button. When you push the lock buttons nothing happens no sound at all. I checked the fuses and it was fine changed it anyway still nothing. I know there is a relay, but can not find it. Does anyone know where it is located? Also is there any other reason the all three buttons would stop at the same time. I now have no way to get in the back hatch because it will only open with the button there is not key hole to unlock it.
Thanks in advance for any help with this!!

 

Here goes..

Diagnostic Chart for INOP power locks:


Wiring Schematics:
Liftgate/Endgate Lock Cylinder Switch Inputs:


BCM Inputs and Outputs:


Relay Control:


Door Lock Actuators:


Let us know if you have any questions regarding the material above.