Welcome to SHOforum, Brett. How many miles on it? PTU fluid may be gunked up. Definitely have the dealer check this out. It could be a wheel speed sensor issue or it could actually be a drivetrain issue. Some 2013s were affected by the halfshaft recall, maybe yours needs the same fix applied to it. Or it may be a part of the suspension/steering. Either way, having it inspected while on a lift should be the first step.
- Wheels/tires
- Brake system
- Wheel bearings
- Halfshafts
- Wheel speed sensor(s)
- ABS module
- Wiring, terminals or connectors
- ATC solenoid (part of rear axle)
- 4X4 control module
BTW, there is no mechanical LSD on these cars.
Four Wheel Drive (4WD) Systems
The All-Wheel Drive (AWD) system consists of the following:
- Power Transfer Unit (PTU)
- Rear driveshaft
- AWD relay module
- Rear axle with coupling device
Torque from the engine is transferred through the transaxle to the PTU . This torque is transferred from the driveshaft to the rear axle, which drives the rear halfshafts. The AWD system, also referred to as an Active Torque Coupling (ATC) system, is always active and requires no driver input.
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.
Serviceable components of the PTU are limited to the output shaft seal and ******, intermediate shaft seal and deflector, and the PTU transaxle compression seal. No internal components are serviced. There should be no need to remove the PTU cover. If any of the internal geared components, bearings, case cover or shafts are worn or damaged, a new PTU must be installed.
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.
