4x4 engaged without touching the button a few days after 3" body lift
 

Back Story: I recently completed a 3" PA body lift. Seemed to go flawlessly. We took our time and disconnected everything that needed it and reconnected everything afterwards. No obvious issues. Got the new 33" tires installed a few days ago. I have put a few miles on the truck but nothing crazy. Few local trips to the store and to a family members house. Maybe 15 miles total?

The Truck: 2001 XLT 4-door 4x4 Stepside Off-Road with 85k on the odometer. Zero previous issues with 4x4 engagement. I've tested it a few times and always worked properly.

Problem: I was leaving my family members house yesterday and the truck slipped into 4x4 high on its own right after I exited the driveway on a subtle right hand turn. I have not touched the 4x4 auto button in months. I noticed right away and pulled over and was able to get it back into 2WD with some fanagling. Drove straight home and parked the truck.

I don't see anything obviously loose or out of place. I can't help but think the body lift clearly has something to do with this.

Any ideas or things to check? I'm at a total loss at this point.

Regards,

Brian

Electric 4WD system is control by the 4X4 module in 2001, it is usually in passenger kick panel or above glove box.

The way it works is using 3 resistors in the 4WD selector switch, similar to how cruise control works.
When key is on 4x4 module sends voltage to Selector switch, say 5volts, if 4 volts comes back from switch then 4x4 module sets 2WD, if 3volts then 4Hi, if 2 volts then 4low.
Just examples, never measured the voltage, could be 12volts, but voltage will be less after going thru the switch/resistors.

4x4 module is also connected to the 4 contacts in the shift motor, these contacts "tell" 4x4 module which "gear" shift motor is in, the contacts open and close based on transfer cases shift rod position.

So if you turn on the key and 4x4 module sees 4volts it checks to see if contacts show 2wd if so it doesn't do anything, if it sees 3volts from switch it would shift to 4hi.

Why did yours shift?
I doubt it is related to the lift unless you changed position of shift motor, or stretched wires too tight and a contact wire is loose, so 4x4 module changed motors position to match selector

Did the 4hi light on the dash come on?
That would mean 4x4 module was involved, it runs the 4wd dash lights based on shift motor contact positions.

Could have been a "one off", slight system wide voltage drop triggered the shift but I would expect it to correct itself once voltage was stabilized.

Wiring diagram here

Hey Ron,

Thanks for the quick response and your time. We definitely had the passenger side kick out to get to the body mount/bolts up there. I can double check to make sure we didn't mess up anything.

We didn't touch the 4x4 shift motor at all. I assume that's on the back of the transfer case. The lift has you disconnect that when you perform the lift. It showed a little bracket to attach after the lift but there was plenty of slack in the line enough to use the factory bracket/harness. I'll double check it again though.

The 4x4 and 4x4 High lights came on in the dash. It's been freezing cold the past few days so it's possible that it has something to do with a slight voltage drop. The battery is newer though. I replaced it last year.

I found a few posts where people had a "one off" with this situation and that would be great if it was the case. Just has me paranoid to take the truck anywhere and get stuck in 4x4.

I'll check the transfer case harness and I guess see if it repeats this problem before I go crazy with the multimeter and the modules.

Thank you greatly for your time Ron.

Best Regards.

Brian

If it were to get stuck in 4x4, it wouldn't be undriveable, just a pain in a parking lot. Now if it starts wanting to try and get into 4 low, then that might be a problem:skull1[1]. Maybe it was just some sorta glitch, i wouldn't be scared to drive it on short trips

I'm sure hoping so GT2000. Took it out today on a short trip and the truck behaved perfectly normal. I'll keep an eye on it.

Regards,

Brian