I also checked the TC and TCM. It locks into 4lo as it should. The front driveshaft is unlocked and spins freely when in 2wd/truck is off and the front driveshaft is locked when in 4hi.

 

Vacuum tested the lines at the wheels and IWEs today.

It seems that the passenger side IWE isn't holding air. Would this cause the grinding sound on the driver side?

 

I found the info about the hub vacuum seal failing in VTX's diagnostic thread. I'm going to go ahead and replace the IWE on the passenger side this weekend.

 

Replaced the passenger side IWE today and it seems to have greatly improved the clunking clicking, and general horrid noises that were happening.

There still seems to be some issue after disengaging the 4x4, a slight ticking noise barely audible at slow speeds when decelerating to a stop. Wondering if there is some damage to the driver side IWE due to everything being out of whack.

I tore the upper control arm boot as well so that's going to need replaced soon, but with 113k it was probably about that time anyways.

 

Sorry I hadn't been back myself but it looks like you are on the right track then.

 

Generally speaking, once you zing an IWE enough (that would be your horrible grinding sound), they're toast. And replacing them in pairs is not a bad option if you can afford it.

 

Wookie

I recently had the cv joint nut work loose on the passenger side which caused sporadic 4x4 issues. This also caused the driver side to not want to engage 4x4. I checked vacuum on both hub actuators, and both were within spec and held vacuum. i tightened up the cv nut which took all the issues away, except the passenger side actuator would not release while in 2wd.

Finally got a chance to take apart the passenger side, and the actuator came out in two pieces. No idea how it was showing steady vacuum. Replaced it and everything works as it should.

Hard to say if I broke the actuator when I tightened it back up and the gears were not meshed or from intermittently engaging. Either way, it was an unnecessary, costly mistake. Don't forget the loctite on reassembly!