Hey folks,

My 2002 ZR2 will not come go back into 2wd. It snowed this a.m. and I pressed my button for Auto-4wd all was good while driving. The roads are pretty much clear and I pressed the switch to go back to 2wd, the light on the switch flashes a bit then cycles back to 4HI. The TCCM is clicking in the kick panel, and the system worked fine two weeks ago after an ice storm.

Vehicle background. The ABS light has been on for roughly 10 months (I know, I know), according to scan tool the culprit is a bad wheel speed sensor. Could this wheel speed sensor issue with the ABS also impact the push button 4WD system?

Any suggestions would be appreciated.

 

This is a C&P from the tech article on the main page.

4wd will not disengage:
Faulty wiring
Faulty lamp
Transfer case vacuum switch plugged or faulty
Vacuum lines pinched
Transfer case vent filter plugged
Actuator cable kinked or damaged
Faulty switch
Faulty encoder motor
Faulty TCCM
Faulty front axle

I think almost all the 4X4 problems are covered on this site...The search engine will be your best friend and you will have some reading to do. I dont think the abs issue will effect the 4x4.

 

Try to determine if it is actually in 4x4 or if maybe just the front diff is stuck in lock....can you hear the encoder motor moving ?

 

Is that the part in the kick panel? If so then I can hear it clicking. Not sure what I should be hearing over tire hum at 30 mph, I'd it's somewhere else.

 

The encoder motor is the part on the transfer case and you can usually hear it moving as well.

 

The TCCM is in the kick panel and is what you hear clicking. Corrosion on the TCCM connector terminals is a common problem that is easy to deal with. Inspect, clean terminals if required, and report please. Also check ATC fuse in the underhood box and the 4WD fuse in the box at the LH of the Instrument panel with a test light (probably they are OK but do make sure).

In the meantime if you have to drive it on dry pavement you can unlock the front axle by removing and plugging the hose leading to the solenoid on the firewall above the distributor.