4X4 not working

New Envoy

Original poster
Member
Oct 20, 2012
56
First off, nice site! But, somebody for got to tell me about it! I was still on the old one. But its ok, Im here now. Working on an 06 envoy denali. When I turn the knob on the dash, the light changes from 2WD to auto and so on. And I can hear the motor on the transfer case working. But, when I "test" it out on a gravel road, only the back wheels spin. Any thoughts, or ideas?
 

dfc739

Member
Jul 29, 2012
170
Des Moines, IA
New Envoy said:
First off, nice site! But, somebody for got to tell me about it! I was still on the old one. But its ok, Im here now. Working on an 06 envoy denali. When I turn the knob on the dash, the light changes from 2WD to auto and so on. And I can hear the motor on the transfer case working. But, when I "test" it out on a gravel road, only the back wheels spin. Any thoughts, or ideas?

Welcome to the site. There is a great 4x4 troubleshooting guide at http://gmtnation.com/f79/4wd-not-working-step-inside-107/

I think that link will help in narrowing down your problem. And it sounds like you're at "Section 3" but it never hurts to go ahead and retry the other sections.

Dan
 

tblazerdude

Member
Dec 4, 2011
321
A common failure on these trucks is the splined disconnect, which is where the 4WD actually engages by use of a fork which is pushed on by a motorized actuator. This actuator is one of the two motorized sounds you hear. The other sound is from the transfer case. Searching and learning about the splined disconnect is where I would start. I could tell I had a problem when the passenger front CV shaft could be moved by hand, up and down, about 1.5 inches.
 

jrSS

Member
Dec 4, 2011
3,950
Don't worry...I never got an invite either. I just happened to be logged on at the time the exodus went on. It was interesting to say the least. So welcome!!!!! U could also try to pull the 4wheel drive fuses in the bcm and fuse box under the hood. Might wanna start there.
 

Sparky

Member
Dec 4, 2011
12,927
First off, welcome! Glad you found us.

To me it sounds like possibly the disconnect on the front right wheel as well. What sometimes can happen is the fork wears heavily, so the fork moves but is disengaged from the collar, so while the system thinks it is engaged it really is not. How many miles are on the truck? Has that disconnect ever been serviced by chance? Also, has the transfer case had its 50K fluid changes? A malfunctioning transfer case can also cause the problem.

Here's what I would to to test to see which is the culprit. Put the truck into 4WD mode, wait for it to say it is engaged. Then shut it down and jack up both front wheels and put the frame on jack stands so the front wheels are off the ground. Now try spinning each wheel by hand.

If the actuator engaged, spinning one wheel should make the other wheel spin the opposite direction and the front driveshaft remain stationary.
If you can spin the wheels and the driveshaft spins, it could be pointing to a transfer case issue.
If you can spin the passenger wheel and neither the driver wheel or the driveshaft spin, then your disconnect is probably shot.

One last thing it could be (though not quite as common) is the front differential could be exploded. But usually that also results in nasty crunchy noises.
 

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