AWD not working?

[Gray Brick]

What was your 60 foot time?

[Vortech347]

What was your 60 foot time?

That stang cutting a 2.2 60' on slicks makes my soul hurt.  haha

You should be around 1.8x at least with your AWD. You might just be coming out too hard and it's a crappy track.

[LSOR]

Changed the PTU fluid and it didn't look bad at all. But then I went out and from 20mph roll I can blow the front tires off. It doesn't seem like the AwD kicks in at all.

If the PTU is bad wouldn't it throw a AWD fault?

[SHOdded]

PTU wouldn't fault out IIRC.  The electronics are in the RDU/ATC portion of the AWD system and of course ABS, so any PTU info is by inference.

And yes there should be power sent to the RDU however momentarily if full throttle is applied

Principles of Operation

The vehicle is equipped with an All-Wheel Drive (AWD) system, also referred to as Active Torque Coupling (ATC), that is always active and requires no driver input. The AWD system has no Mode Select Switch (MSS).

The AWD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is delivered to the front wheels. If wheel slip between the front and rear wheels is detected, or if the vehicle is under heavy acceleration, the AWD system increases torque to the rear wheels to prevent or control wheel slip. When the AWD system is functioning properly, there should be no perceived speed difference between the front and rear axles when launching or driving the vehicle on any uniform surface. Traction should be similar to a part time Four-Wheel Drive (4WD) system in 4H (4X4 HIGH), but have no binding in turns.

If the spare tire is installed, the AWD system may disable automatically and enter Front Wheel Drive (FWD) only mode to protect driveline components. This condition may be indicated by an AWD OFF message in the message center.

If there is an AWD OFF message in the message center from using the spare tire, this indicator should turn off after reinstalling the repaired or replaced normal road tire and driving a short distance. It is recommended to reinstall the repaired or replaced road tire as soon as possible. If the sizes of the tires used on the front and rear axles differ greatly enough, the AWD system may stop functioning and default to FWD or damage to the AWD system could occur.

AWD faults may be indicated by the powertrain malfunction (wrench) message center warning indicator in the Instrument Panel Cluster (IPC) as well as the Check AWD message center warning indicator in the message center.

The AWD system consists of a Power Transfer Unit (PTU), 4X4 control module, rear axle and a solenoid-actuated ATC device. Based on the amount of current sent to the clutch, the module varies the torque sent to the rear wheels by sending a duty cycle to the ATC device, located inside the rear axle. For concerns with the PTU , refer to Section 308-07B .

The 4X4 control module also provides the brake system with its current clutch duty cycle and determines whether or not the brake system may take command of the clutch duty cycle.

NOTE: The Active Torque Coupling (ATC) solenoid is not repairable. If a new component is required, the ATC solenoid and rear axle are installed as an assembly. Refer to Section 205-02 .

The active, on-demand AWD system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the ATC solenoid that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are:

Accelerator pedal position via the High Speed Controller Area Network (HS-CAN)
Transaxle range from the PCM via the HS-CAN
Brake system status from the ABS module via the HS-CAN
Wheel speed from all 4 wheels from the ABS module via the HS-CAN
4X4 control module outputs are:

Solid-state clutch (Pulse Width Modulated (PWM) signal) to the ATC solenoid
Percent of torque transfer commanded signal to the ABS module via the HS-CAN
Torque request available signal to the ABS module via the HS-CAN
Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the AWD system detects an overheat condition, it enters a locked mode. If the heat in the AWD system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. This condition may be indicated by an AWD OFF message in the message center. Allow the AWD system to cool down at least 10 minutes with the ignition switch in the ON position.

Active Torque Coupling (ATC) Bar Code
The AWD system on this vehicle is equipped with a bar coded ATC to reduce the tolerance of electrical current to torque delivered by the ATC solenoid. The ATC bar code can be found etched on the ATC wire harness connector protruding from the top of the rear drive axle. The 4X4 control module uses this bar code information to match the clutch characteristics of the ATC with the desired output torque. If the bar code information does not match the 4X4 control module information, driveline damage or driveability concerns can occur. Therefore, if the 4X4 control module or the rear drive axle needs to be replaced, the 4X4 control module will need to be configured with the ATC bar code information.

[LSOR]

So it's been raining here for the last 5 days. I've been driving around and when I turn the traction control off I can spin the front tires for a second or two then I can feel the back tires start pushing I think I juts need to flush the PTU a few times and should be able to get a few more miles out of it at least.

[SHOdded]

how is tire pressure and tread looking at each wheel?  In Forscan, I can monitor the wheel speed sensors to know if the reaction times on my AWD Edge, I am sure there is something similar in Torque Pro?  Logging that data, along with what the TPMS is reporting may help find a solution.

[LSOR]

Do you don't think flushing it again is a good thing to do?

[SHOdded]

never hurts!  but if the fluid looked good last round, the hope is it will be even better now.  Then we would have to look to other possible culprits.