The power lock button on both doors only lock / unlock the drivers door.. All other doors must be manually controlled. Does anyone know the possible cause?

it would help to know what it is?

Probably a Monte Carlo SS, it would definitely help to know the year though.

Sorry, 05 Impala SS

if the driver works you know the tan from BCM pin E and all the gray wires on the bottom are good. but if the others dont work i would look at the tan wire from BCM pin h

I had the driver side door lock stop working on an 03 Impala, I pulled all three of the connectors off of the BCM and did a continuity check from the BCM to the switch, found it was something in the left IP junction block which might be reresented by the "C" numbers in the schematic. What ever yours is will be something in common for both switches. Don't stick a probe into the contacts on the connector, since those connectors are not weather pack you probably can back probe the connectors.

Might be a good idea to disconnect the negative battery cable. There may be current present with the ignition off, i think the way the PCM works is the door lock solenoids have the correct voltage applied, then when u press the switch the PCM connects the output to ground completing the circuit.

Since the car is still under warranty, I'll let the dealer take care of it. I'll post the results, I'll check the connectors and wiring to make sure they're snug.