I have a 2001 4X4 and having trouble with the crappy vacuum boot. I was told that since mine has the auto 4X4 option as well as the 3 buttons that I could be opening up a jar of worms that would not be a pretty sight! What exactly would happen if I put the cable on the differential to replace the vacuum boot? I never use the auto 4X4 button, I always either push the buttons manually when I want it to be in 4wd or 2wd, if that makes a difference.

 

I cannot find the thread right now, but I do remember another member doing the posi-lock system on his truck which had the NV236 transfer case. He stated that unless he did things a certain way, the TCCM would lock into 2wd and set the 'service 4wd' light. IMO, that is just as bad as not having the front axle engage...

 

What exactly is the TCCM and what does it do? transfer case control module?

 

Precisely. It controls the transfer case and everything about the 4wd system on your vehicle.

 

I looked for the thread too but no luck. I guess the easier way is just replace the stupid vacuum actuator. I actually took it off back last fall and patched 2 small holes in the rubber, it has worked for a year now but the little "patches" are starting to come off causing it to leak again.