Don't get mad. lol. I'm not making this up, I'm taking the info right from the GM service manual. But you can try lifting the back wheels, blocking the front wheels pulling it in drive and I garantie you the rear wheels won't turn. Don't go away, nothing wrong with a good discussion. Good dialogue is what forums are for, that is the way we discover the truth. Feel free to paste your findings that this is an all time AWD an I will bow and acknowledge. I've been wrong before, I'm just going by GM's manual.
I had the driveshaft off of my Trax all of last summer didn't notice any difference in mileage at all. Seems to me if it was active 100% of the time it would have effect on mpg.
The rear drive axle system operates as follows:
The system distributes torque to the rear wheels to enhance traction and improve vehicle
The all wheel drive (AWD) clutch assembly contains an electromagnetic coil, primary clutch, a
ball cam, a secondary clutch, and a rear differential clutch control module.
The rear differential clutch control module uses wheel speeds, steering angle, lateral
acceleration, yaw, chassis control intervention, and other signals to determine the torque to be
applied. This data is transmitted via the vehicles Controller Area Network (CAN) from other
modules and sensors in the vehicle.
The driver information center can display two messages for the Rear Drive Axle system.
Service All Wheel Drive or code 73 and AWD Off or code 173. When these messages are
displayed, the system is disabled and the vehicle will default to 2WD.
If the vehicle is being driven very aggressively or an unexpected tire size has been used, the
AWD Off or code 173 message will be displayed in the driver information center. This should
not result in the replacement of rear differential clutch control module.
The AWD Off or code 173 message will be displayed in the driver information center if the minispare
tire or a very small sized tire has been installed. This should not result in the replacement
of rear differential clutch control module.
The torque transfer to the rear wheels is controlled by the rear differential clutch control module
which sends current to the electromagnet coil in the clutch. The coil applies a load on the
primary clutch which rotates the ball cam loading the secondary clutch. The secondary clutch
applies the torque from the drive shaft, driving the rear wheels. Safe current range is between
0-6.0 A. If the current is out of the specified range, a DTC will be set, and the driver information
center will display the Service AWD or code 73 message.
The rear differential clutch control module has an internal temperature sensor, which will
maintain consistent and continuous temperature compensation for torque transfer from -40°C to
+120°C. When the temperature of the module is determined to be beyond its limits, the rear
differential clutch control module will temporarily disable the rear drive system and the driver
information center will display the AWD Off or code 173 message. When the temperature of the
module is back within the limits, the rear differential clutch control module will enable the rear
The rear differential clutch control module monitors the outside air temperature maintaining
consistent and continuous temperature compensation for torque transfer from -20°C (-4°F) to
Voltage to the module is between 9-16 V. The module will set a low voltage DTC and a high
voltage DTC to indicate voltage value out of range.