Ok, your door locks don’t work. And you checked both switches (driver side and passenger side) and both directions (lock and unlock). Still nothing.
You’ll need to check TWO fuses. One of them is called Courtesy (CTSY) and it powers the switches and relay. The other one is actually a breaker and it’s marked as PWR ACC. Replace blown fuses if necessary.
Wiring diagram (applies to virtually all 3rdgen f-bodies)
You can start from the easiest: remove the switch from the door panel (careful, some of the screws are faux plastic screw heads, just a decoration, do not remove those) and remove it from the connector and do a simple test.
Measure the voltage on the orange wire (or use a test light). You should see 12V. If not, you have a wiring problem between the fusebox and the door switches.
Using a paperclip, jumper the orange wire to the blue wire and then the orange wire to the black wire. If that works, the switch is faulty. If it doesn’t work, it’s probably the relay or wiring.
You can find the relay behind the driver side kick panel, in the hollow part of the A pillar. It will be very likely covered in a lot of goo (to protect the relay from moisture and other elements).
Test the orange/black wire for 12V. No voltage? Bad fuse or wiring.
Don’t forget to check the ground on the relay!
Put 12V on the thin blue wire and then do the same for the thin black wire. Did the relay click both times? No? Bad relay.
If it clicked, that’s good, it has power. Did the door locks move? Yes? Your problem is in the wiring between switches and relay then.
Still no door lock operation? Remove the connector from the relay. Put ground on the thick grey wire. Put 12V on the thick tan wire. Door locks work? The relay is bad. Replace it.
Door locks still don’t work? Possibly bad wiring harness but probably bad door lock motors.
Hope this helps.
ATGO is not responsible for any damage done to your vehicle by following the above instructions.