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Discussion Starter · #1 ·
'04 Envoy, 4.2L, noticed a whirring sound from the front on the highway the other day in 2HI. Got home and put up on jackstands, all 4 wheels off the ground:
  • 2HI - in drive, back wheels spin as normal
  • both actuator motors make sounds when shifting between 2HI and 4HI
  • 4HI - in drive, back wheels spin, front driveshaft spins, front wheels do not spin, clicking sounds from front right
  • Engine off, spin front wheel by hand, opposite side spins opposite direction
This leads me to believe the front diff is okay? But the front actuator has had a mechanical failure of some sort, does this sound about right? Am I heading the right direction?

Thanks!
 

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'05 Chevy TB EXT
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5,138 Posts
One cannot assume the differential is okay until it is eliminated first.

You could have a busted side gear or spider instead.
But it's usually the slip/fork/stepper motor at fault <pick 1 or 2 or all 3>​
 

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My ‘05 Trailblazer had that issue also so I ask another mechanic about it and he told me It was the actuator not putting it all the way into 4wd. He told me if you don’t use the 4wd much then it tends to get Stuck and not work properly. And he was right for my case… I just switched it back and forth a few times until it finally started going in and out smoothly. And i take it off road in 4wd every once in a while , haven’t had the problem since. mabey this will work for you. There’s nothin more aggravating than needing 4wd and it not locking in , !#@! Or, it getting stuck in 4 low. Mine did one winter for a few days til the weather warmed up.. good luck ✌😎
 
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