For those located under the dash in the middle of the cab behind the stereo.
Power door lock relay wiring.
If the relay and switch are working properly but you re not getting power and ground at the door lock actuator check the wiring harness in the hinge area of the door.
That s where most wire breaks occur.
Remove the old door lock relay.
Should you need to add relays for a 3 wire negative type b door lock system just change both normally open terminals 87 from 12v to ground.
Here s a power door lock wiring diagram for a 2009 chevrolet malibu.
Remove the panel that covers the area under the stereo.
Locate the door lock relay.
If your alarm or keyless entry has positive outputs only you will have to connect the other side of the coils to ground and connect your outputs as shown.
Using a pair of needle nose pliers pull out the old relay.
Using a mechanical latching relay like the pcb latching relay pictured here you can use a single negative output to alternately lock and unlock the doors.