If all of the door locks are inoperative start your diagnosis at the fuse box.
Gm power door lock troubleshooting.
Then use your test light or digital meter to check for power and ground at the connector when you operate the lock unlock switch.
You should see the voltage polarity toggle with each switch activation.
For vehicles equipped with door lock cylinders the door can still be opened using the key.
An inoperative power door lock can be caused by the switch solenoid wiring problem or mechanical problem within the linkage of the affected door.
If the power door lock relay fails it will cut off power to the entire power door lock system and may cause them to not function correctly.
However vehicles without door lock cylinders will not be able to lock or unlock the doors until power is restored.
Unplug the door lock actuator electrical connector.
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Inspect the fuse that protects the door lock circuit to ensure it is not blown.