when I turn the switch to put my truck in 4 wheel drive I can hear it clicking inside the dash but the light for 4x4 does not come on and the front wheels don't lock in. Any ideas where to start

 

usually....one needs to check the front axle for a vacuum leak.

If that is all good, no vacuum leaks...then the actuator (what the vacuum line attaches to), might be seize...they tend to do that from lack of use.
It can be removed and with your favorite spray lube (wd40, kroil, blaster...etc) & some simple tools you might be able to get this to free up.

 

It will not lock in at the transfer case

 

then T-case is the issue...might be a simple electrical connection or something far greater like stripped gear....hopefully your T-case does not have water in it and is froze. does it even have oil in it?

 

Yeah I can turn it manually but I lose power from the switch to the motor on the t-case

 

have you check the relay or fuses for the T case?

more info you may find useful
Rebuild Kit BW4406 Transfer Case and Parts plus Illustration drawing and parts list! - Drivetrain.com

or
4x4 Woes - F150online Forums

 

Is there a inline fuse anywhere

 

doubtful if any "inline fuses"....but

so you checked the #3 & #23 fuses and the larger "maxi fuse #104...yes?
So...also...No vacuum leaks to the actuator and the plunger rod under the actuator moves freely.

Also...the T-case has correct oil and level in it.
^^^ all true^^^?

have you had a front windshield replaced or is leaking?
Is there anything else strange going on inside the cab...lights flashing or turning on or shutting off? The Heater and A/C is placing air where it is suppose too?? also check for vacuum leak...behind the battery.

you probably need some assistance checking the T-case motor....check the amp draw as the switch gets rotated to each position. maybe the T-case motor is weak??

or maybe the switch on the dash is not providing power to the T-case motor...hopefully a simple switch is all or a bad wire....but....

there is a "GEM" module inside the dash that controls the tranny and T-case and other major fuctions, that can short out...usually if that happens you get all kinds of strange electrical activity...I think it ties into the anti theft...so it maybe a dealer only replacement?...so that they can tell all the electronics that everything is OK after the replacement.

more info on GEM >>>https://www.ford-trucks.com/forums/1...ogramming.html

 

If if works I 4 low but not 4 hi than it is the gem module or selector switch. 4 hi and 4 low use the same wires and relays to move the encoder motor. What you are hearing is the relay for the synchronization clutch inside the transfer case. Since the gem is sending a signal to the clutch relay but not shifting the case I would go with the gem module having an issue.

 

It ended up being a broken wire on the gem module and the shorted out the switch in the dash too

 

so you had the "AHH haa" moment

glad you got it fixed

Merry CHRIST-mas