Mechanic says when he hooks up his diagnostic tool, it says there is no communication with the 4wd computer. The lights on the switch don't light up and 4wd does not engage. I have had this problem ever since the truck came back from the transmission shop.
Check the wiring to the actuator on the transfer case. See if there is power to it. If there is, remove the actuator and check it for operation. If no power, work back to the relay and switch to see where power is lost.