I have an '06 Lariat 4x4 and about 5 months ago the 4wd wouldn't work, turn the switch, nothing happens, no light, no 4wd. Parked the truck, ate dinner come back out, it works. Up north last weekend no 4wd at the boat launch, and then going to leave and every light on the auto climate control is on, but nothing is actually on. Pull the battery when we stopped for gas, hook it back up, everything works including 4wd. yesterday again I test 4wd and nothing, pull the battery good as new. Sounds like GEM module to me. What do you guys think? If so where is the best/cheapest place to buy on and how much am I looking? PLus, does Ford have to program it?

 

Bump