My truck has the Auto-trak transfer case. It is a NV 246 AFAIK. It has 4 engagement buttons. The top one is for Auto 4WD which is the same as modified AWD. The transfer case has clutches that engage when the rear loses traction. So this truck has selectable AWD but not full time AWD. It is probably a little different because when the vehicle senses a loss of traction (at the rear wheels), the system will automatically engage four-wheel drive. AWD on the other hand progressively increases traction to the front depending on the loss of traction sensed at the rear wheels and is therefore variable. So this is probably the option they are referring to and is not really AWD.

 

i read it during physics class, i thought he said that the 4wd on the truck was as close as he could come to AWD like the SS? or not

 

The wifes ride...2004 Tahoe has stabili-trac...you guessed it..AWD..only buttons on the dash are to disable/enable traction control and another to lock in low range..thats it...truck handles awesome in the bad weather...should hook real good once its force-fed.

 

Yes, I called the Autotrac an AWD transfer case in the article. In hindsight I wish I had done some more research on the differences between the Silverado SS's AWD and the K1500's Autotrac option but I just ran out of time and mental horsepower.

The Autotrac is a $375.00 option, that must have been a typo that made it to publication, I don't have the article in front of my to confirm.

Definition aside, the Autotrac has worked really well for me with the power levels I have right now and kicked butt at the autocross. It was a rainy day and I never once got the truck loose as long as it was in Auto 4wd.

 

Research complete, here is the story on the Autotrac transfer case.

According to Volume 1, page 4-497 of the Chevrolet Factory service manual,

"During normal driving situations, the transfer case can operate in the Auto 4WD mode. In the Auto 4WD mode, the transfer case shift control module monitors rear wheel slip speed, based on the inputs from the front and rear propshaft speed sensors. When the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor. This motor rotates the transfer case control actuator lever shaft, applying a clutch pack. This clutch pack is designed to deliver a variable amount of torque, normally delivered to the rear wheels, and transfers it to the front wheels. Torque is ramped up to the front wheels until the front propshaft speed sensor matches that of the rear propshaft speed sensor. Torque is ramped down to the front wheels. The process would repeat if rear wheel slip is detected again. "

 

Good info John.

If the clutch pack is serviceable it might be better than the full time AWD case since the viscous coupling it uses is not serviceable.

You don't have to be turning all the extra driveline mass all the time either.