So, I did a search here and all I can find are issues with the doors not unlocking. My issue is the reverse. My doors won't lock.

The alarm will set with both the lock button on the key, and by inserting the key and turning the drivers door lock cylinder, however none of the doors will lock. I can push the dash mounted lock and hear a relay clicking under the steering column but none of the door motors work.

CDL unit maybe?

 

Check the wiring at the body control module. If none work, that's where I'd start. You should be able to hit the lock button on the remote as well as the inside button and there should be voltage at those pins. Also, just for sake of simplicity, check the relay itself. If you hear a click, be get no action, it might just be a worn relay.