I'm lost for words... Issue after issue!! 2 years ago it was the plastic fork shifter replacement in the transfer case = $1,000 to the dealer. A year ago I had the dreaded head gasket and cylinder head replacement = $2,800 to the dealership. Today I need some help from you Hummer experts on what I'm dealing with. Driving down the interstate in normal 4Hi going about 60mph my rpm's reved and it was like I put my car in Nuetral. Coasted to the shoulder and no gear would work not even reverse. Heard gear grinding when shifting to Park. Put 4Hi Lock on and drove perfect. Tranny shifting smooth etc. Made it back to the house and switched it back to Normal 4Hi. No engagement or drive ability. I put parking brake on, put shifter in Drive, then got underneath my car and heard a grinding noise in my front differential. Also noticed some differential fluid on right axle. Front differential had fluid when I checked it. Do I have a busted front differential or am I looking at a transfer case repair??? Like I said, grinding noise in front differential when in Drive or reverse in 4Hi normal. Please help!

 

Driving back home in 4hi locked. Hopefully that was a short distance ?
How many miles on your rig?
Sorry I am not able to help, I'm a noob.
The aces will be here shortly I assume lol.
I recommend the forum search feature. I feel like I've read about this before.. You might find some answers.
Good luck

 

I was driving home in Normal 4Hi when the problem occurred. Drove about 5 miles slow in 4Hi Lock. I've got 130k miles.

 

Sounds like front diff went.

The Tcase will send all the power to the front in 4HI when there is no resistance due to a blown diff. The vehicle will not move until put in 4HI LOCK.

 

So differential is damaged?
Lol. I'm not an expert either.
Chris

 

I have a somewhat similar issue, BUT my normal 60/40 AWD is working but when I try 4 hi lock the button does not blink, nor does 4 hi lock engage. No CEL on or anything. Any thread suggestions or advice on any of our issues? 4 Lo works just fine. 4 hi is the only one not working. No idea. If the transfer case motor is bad would it still make it to 4 Lo just fine? Or another issue? HELP!!!!!