Sorry for the delay, I was out for supper with my family.
Forget the TREC fuse.
Check this, with the transfer case in 4wd, unplug the front axle actuator. TEst with a test light between brown and light blue, see if there is power. If not then see if there is light between the brown and the chassis ground.
To the front axle actuator. not the switch on the case.
STill no power there, ok, go back to that 4wd fuse in the left dash fuse block. Check it with the test light.
It goes out through the main connector through the fire wall, under the fuse block under the hood, then onto a connector on the inner fender, drivers side then on to the front axle actuator.
You could run a wire from the battery to that for testings. The wire goes directly to the front actuator and is battery voltage.