I have a 2004 GMC 2500HD. For years I ran it with 85hp performance tune until I screwed up and forgot to re-tune the truck prior to towing a travel trailer. I limped the Allison (only one time). I reconnected the Predator and returned the truck to the stock tune. Now, all of a sudden, I have lost the ability to go into either low or high 4WD, am getting the "service 4WD" message on the dash console, and no lights are appearing on the 4WD switch. I have pulled the switch and checked the resistances when the different buttons are pressed, and they are all within normal limits. Is there any chance that somehow the transfer case control module went to sleep because I reverted to the stock tune, or does the Predator affect this part of the truck's electronics at all?
Thanks a lot,
DRJ