Hello all,
I am a long time reader, first time poster. Thanks for all the info I have seen so far. I have done some reading of other threads, but can't decipher if any of the issues are the same as I am having. So here it goes...

I have a 1997 Ford F150 4x4 4.6L extended cab with 180000 miles. Rusty but trusty. I have had 4x4 engagement issues before with the truck, and ended up having to replace the front axle shifter fork and collar. Thanks to forums like this, it was possible for me to do myself. Now I have a different issue. The 4x4 light will not come on at all when in 4 hi or 4 low in with the transmission in neutral. The things I have done are check every single fuse the truck has, all are in working order. I have replaced the shifter switch with a known working used one, no luck. When I turn the ****, I hear clicking from the relay in the middle of the dash, but the 4x4 light does not come on. The front driveshaft is able to be spun when I have the **** in the 4 hi or 4 lo position. I have pulled the GEM module out to see if I had the dreaded windshield leak issue, and it appears that all connections look great, and there does not appear to be any burn marks on the circuitry. I also tested to see if the vacuum solenoids were getting the correct signals. It only stays on 2 wheel vacuum (by testing the ground connection to the solenoids), it does not switch when I turn the ****. So at this point I am under the belief that I have an issue with the transfer case shift motor or something related, and that when it does not work, it does not give the signal to the vacuum solenoids to switch or allow the 4x4 light to come on. If I am correct, how do I test to see what is the issue at the transfer case?

WOW that was a long post. Hope someone out there can understand what I am saying, as I am not a pro mechanic by any means (as if you couldn't tell by the post) Thanks in advance for any help!!!!!

 

A better code reader may give you more direction. I bought a wifi code reader online for $15, downloaded a free laptop program and gave way more codes than my old $75 reader. I thought my 03 F150 4x4 was staying engaged in 4x4 periodically. I did get a historic code, that seemed relevant, but I can't find where I put it. But I haven't seen a similar issue in a while.

 

Yes, the case motor closes a ground through the case motor circuit board to operate the firewall solenoids.
This sends a ground back to the control module to cause the GEM to light the dash lamps.
The clicking is the motor has not engaged for some reason.
Good luck.