4 wheel drive is not responding

HMAC300

MECHANIC
48,601 POSTS

If you scanned for codes with a typical auto parts scanner these codes won't show up. You'll have to have a pro scan it for you. This may be a trans module problem or an actuator for the tcase but the stabiltrak has to deal with the abs system.

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Sunday, April 7th, 2019 AT 9:03 AM (Merged)

ROCKSIDE

MEMBER
1 POST
2006 CHEVROLET TRAILBLAZER
6 CYL
4WD
AUTOMATIC
31,500 MILES

Hi, I have a 2006 Trailblazer (Extended) with 4 Wheel Drive. It works great in 2WD or 4 Wheel High. However, when I set it to "Auto" and I drive up a hill, something seems to "Slip" / "Clunk" about every 3 seconds. I took it to the dealer and they "could not find anything wrong" and asked if I was driving on Ice or in wet conditions. I have tested it in completely dry conditions and it always portrays the same symptoms when driving up a hill. What is likely the issue?

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Sunday, April 7th, 2019 AT 9:03 AM (Merged)

DENNYP

MECHANIC
1,824 POSTS

Sounds like a worn clutch pack in the transfer case.

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Sunday, April 7th, 2019 AT 9:03 AM (Merged)

BRIAN 1

MECHANIC
1,030 POSTS

Might want to look at this bulletin, just went throught this at the shop. Subject: Misfire Bump or Multiple Bumps after a 1-2 Upshift

Models: 2004-2007 Buick Rainier

2002-2007 Chevrolet Trailblazer 4WD

2002-2007 GMC Envoy

2002-2005 Oldsmobile Bravada

2005-2007 Saab 9-7X

Equipped with All Wheel Drive RPO NP4 or 4 Wheel Drive RPO NP8 The condition can be perceived as an engine misfire, surge or bump typically during or just after the 1-2 upshift. This condition can occur on Bravadas, 9-7X's and Rainiers NP4 Full time AWD. This will only happen in Trailblazers and Envoys NP8 when AWD (auto mode) is selected. When viewed through the TECH II, misfire counts may be occurring but not enough to set a misfire DTC. The concern will be eliminated in Bravadas and Rainiers with the ATC fuse removed or in Trailblazers and Envoys when 2hi or 4hi is selected. Inspect tire pressures and adjust as necessary. Swap the wheels and tires from another identically built vehicle that does not exhibit the concern. If swapping the wheels and tires does not improve the condition, drain and fill the transfer case with AutoTrac II fluid and re-evaluate the condition.

This is likely a characteristic of the vehicle and some degree of this condition should be expected on all of these vehicles. Comparing this vehicle to an identical vehicle with similar mileage should verify this is a design characteristic. The dealer should have looked at this bulletin and tried this first to see if the problem went away.

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Sunday, April 7th, 2019 AT 9:03 AM (Merged)

KIëTTESSEN KOOLA

MEMBER
1 POST

Hi, I'm Alessandro, and I write from Italy.
I have a 4.2 ltz trailblazer from 2003, and I have a problem with the 4x4 switch. In Italy it is difficult to find good mechanics for American cars, and before making empty attempts, I would like to ask for advice here.

The 4x4 switch lights only come on when I start, while driving is off, if I try to insert the 4x4 this doesn't work, unless I turn off the car, set the switch to 4x4, and turn it back on, in this way I get all-wheel drive.
To return to the two-wheel drive the same system, I turn off the car, set the switch to 2h and restart the engine.
Has anyone ever experienced the same thing? And if so how did you solve it?
Thanks for help.