Transfer case keeps trying to engage 4WD

[TNT]

The truck's been sitting for 3 weeks. I start the engine to warm it up and I start to walk away; I can hear the transfer case trying to engage, then release, then try to engage and so on. I open the door to verify it is in 2 wheel drive (electric operated 4WD), and it is, but the dash indicator is slowly flashing 4 low. Then I turn the knob to 4WD and the indicator flashes a couple times then stays on solid (like normal). I get in to move the truck, it is still in 4WD, I move a few feet then select 2WD; the transfer case starts engaging and releasing and the 4 low light flashes slowly again. I switch between 2 and 4WD repeatedly while moving forward and then reverse. Nothing changes. So I try selecting 4 low, no indication and then the transfer case neutral light blinks, but I'm in 4 low! WTF? I tried for over an hour, and yes I even read the operating manual, nothing changed from what I have previously described.

I drove down my drive, then backed up the drive and was about to give up as it was dark now, when things really got stupid. The head lights started flashing, the transmission position indicater lights all lit up, the "transmission temperature high" light came on and the engine shut off. The engine would start right back up, but would die right away. I gave up for the evening.

 

[rbattelle]

Sounds like multiple computer problems. Could also be a bad ground somewhere that's affecting every computer, but it's hard to say. If the vehicle has warranty remaining, the dealer should be able to diagnose the system using his equipment.

Ryan

 

[sag2]

Up until you add the other strange electrical things, the most common cause of the transfer case shifting on it's own is a short in the 5v to the transfer case shift motor. The system works on a MUX circuit and when the voltage changes it thinks you asked for a shift. Add in the other problems and bad ground is a good source. Also look for rodent damage since it has been sitting, or a water leak at either A pillar into a connector.

 

[JWadford]

Up until you add the other strange electrical things, the most common cause of the transfer case shifting on it's own is a short in the 5v to the transfer case shift motor. The system works on a MUX circuit and when the voltage changes it thinks you asked for a shift. Add in the other problems and bad ground is a good source. Also look for rodent damage since it has been sitting, or a water leak at either A pillar into a connector.

mine did this after a really deep water drowning incident, i unplugged everything and dried it out and it went away.

 

[TNT]

Problem found! Rodents have chewed on the main harness.