2000 F-150 7700 4X4. 230,000 miles. Manual shift transfer case. My low range light stays on most of the time, althought I rarely put it in low. It will go off during deceleration. I checked my vacuum hoses and solenoids under the hood and they appear to be working fine. Good voltage, good ground. Axle thingy goes in and out. I even changed the GEM. I changed the switch on the front of the transfer case. I need some help on what to check next. I don't think the low range has any thing to do with the front axle, it should be in the transfer case. Let me know if I am wrong.

 

Sounds like a short in the wiring near the transfer case possibly.

 

I found the problem and fixed it. Awhile back I had the transmission rebuilt. Apperently, the wiring harness was inavertantly moved in between the firewall and exhaust manifold. Some electric and friction tape cured it. A tie wrap will prevent it from happening again.