Olds AWD problems

[PoorRichard]

2004 Bravada Symptoms: Jerks and Shudders at very low speeds only when turning the wheel. The more turn, the more violent the Shuddering. This only happens part time. This makes me think it is an electronic problem. This happened first about 2 years ago when car had about 40K miles. Now doing it again with 60K miles.
I believe this may actually be occurring only when the AWD in engaging the front wheels. My solution: I actually can do without the AWD. How do I disable the front wheel drive? Is as simple as disconnecting.

AWD Description of Operation.

This type of AWD basically delivers torque only to a primary driving axle unless reduced traction is experienced. At that point, the system electronically or mechanically will apply torque to the other axle. Depending on the type of system, this can provide up to 100% of the torque to the axle with traction. These transfer cases use an electronically actuated clutch pack, to allow for a difference in speed between the front and rear axles. An example of an electronically controlled version of the On-Demand AWD is in the Smart Trak system in the Olds Bravada as well as Envoy and Trailblazer.

[gmtech1]

What did you do to correct it at 40k? Unplug the encoder motor and see if it still does it.

[Chris Stewart]

I agree with gmtech1. Unplugging the AWD fuse will stop the engagement if it's not stuck on due to the encoder being messed up.
Because normally the rear wheels are driven and front wheels are activated when needed, removing the front drive shaft shouldn't cause any problems other than the vehicle being stuck in 2WD, not having the front wheels available to help pull your Bravada imo.

[PoorRichard]

Originally Posted by gmtech1

What did you do to correct it at 40k? Unplug the encoder motor and see if it still does it.

After having the vehicle towed to a chev dealer they said it is the transfer case bearings and it would cost $1900 to repair. They said it was not an electrical problem. I went down and picked up the car and drove home with no problems (apparently AWD was now off) Then I simply pulled the fuse marked AWD and it has been running fine.
poor-richard

[PoorRichard]

Originally Posted by Chris Stewart

I agree with gmtech1. Unplugging the AWD fuse will stop the engagement if it's not stuck on due to the encoder being messed up.
Because normally the rear wheels are driven and front wheels are activated when needed, removing the front drive shaft shouldn't cause any problems other than the vehicle being stuck in 2WD, not having the front wheels available to help pull your Bravada imo.

I simply pulled the fuse marked AWD and the car has been running fine. The Chev. dealer said it was not an electrical problem. They wanted to replace the bearings on the transfer case for $1900.
poor-richard

[Chris Stewart]

Good work, thanks for the update.
I think I'd check with another dealer before shelling out $1900.
I believe the transfer case would be noisy even with the AWD fuse pulled if there were bad bearings.

[old_master]

The transfer case in your 2004 Bravada requires the blue Auto-trak fluid. Over time the fluid loses its lubricating ability. The clutch pack in the transfer case doesn't operate smoothly and causes the vehicle to "crow-hop" when turning. GM dealer has the Auto-trak fluid. Drain the transfer case & refill. Drive it for 100 miles, drain & refill again. Should be good to go.