AdvanceTrac ® System

The AdvanceTrac ® system combines the traction control feature and the ESC feature.

Traction Control 

The ABS module continuously monitors and compares the rotational speed of the drive wheels in relation to the non-driven wheels. When the drive wheels begin to spin faster than the non-driven wheels, the ABS module modulates brake pressure to the appropriate brake caliper(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to eliminate the wheel slip and sends this torque reduction message to the PCM over the HS-CAN. The ABS module also sends a traction event message to the IPC over the HS-CAN. When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives traction event message, it flashes the sliding car icon.

Once the driven wheel speed returns to the desired speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the sliding car icon. After the vehicle speed exceeds 100 km/h (62.1 mph), traction control is accomplished only through the PCM torque control.

The ABS module disables the traction control function if there are any wheel speed sensor or solenoid valve DTCs present in the ABS module. The traction control function is also disabled if there is a communication error between the ABS module and the PCM. When the traction control function is disabled, the ABS module sends a message to the IPC over the HS-CAN to illuminate the sliding car OFF icon.

Electronic Stability Control (ESC) 

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input and the yaw rate sensor input with the actual vehicle motion. The SCCM (vehicles with active park assist) or PSCM (vehicles without active park assist) sends the steering wheel angle and rate of change information to the ABS module over the HS-CAN while the RCM sends yaw rate sensor information to the ABS module over a private HS-CAN. If the ABS module determines from the inputs the vehicle is unable to travel in the intended direction, the ABS module modulates brake pressure to the appropriate brake caliper(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to eliminate the wheel slip and sends this torque reduction message to the PCM over the HS-CAN. The ABS module also sends a traction event message to the IPC over the HS-CAN. When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives traction event message, it flashes the sliding car icon.

Once the vehicle instability has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the sliding car icon.

The ESC function does not operate with the transmission in REVERSE. The ABS module disables the ESC function if there are any wheel speed sensor, stability sensor or steering angle sensor DTCs present in the ABS module. Also, if there is a communication error between the ABS module and the PSCM, the SCCM or the RCM the ESC function is disabled. When the ESC function is disabled, the ABS module sends a message to the IPC over the HS-CAN to illuminate the sliding car icon.

Disabling AdvanceTrac ® 

On vehicles not  equipped with the SHO performance package, the traction control system can be disabled by the driver through the menu in the message center by changing the TRACTION CNTRL setting in the message center from ON to OFF. This is independent of the ABS and ESC functions, which cannot be disabled by the driver. When the driver disables the traction control function through the message center, the IPC communicates traction control system status to the ABS module over the HS-CAN and illuminates the sliding car OFF icon. The ABS module takes no further action in regards to traction control until the driver activates the function or until the ignition is cycled from OFF to ON.

On vehicles equipped with the SHO performance package, the AdvanceTrac ® system can be disabled by the driver through the use of the stability-traction control switch. This is independent of the ABS function which cannot be disabled by the driver. When the switch is pressed, a ground signal is sent to the IPC. The IPC communicates AdvanceTrac ® system status to the ABS module over the HS-CAN and illuminates the sliding car OFF icon. The ABS module takes no further action in regards to traction control until the driver activates the function or until the ignition is cycled from OFF to ON.

The driver disables the AdvanceTrac ® system in the following manner:

• Traction control switch pressed momentarily 

  : traction control is disabled, ESC is enabled.

• Traction control switch pressed twice with the brake pedal applied 

  : Sport mode is enabled, traction control and ESC are enabled with modified intervention thresholds.

• Traction control switch pressed and held for more than 5 seconds with the brake pedal applied and accelerator pedal NOT applied 

  : AdvanceTrac ® OFF mode, traction control and ESC are both disabled.

• Traction control switch pressed after deactivation 

  : AdvanceTrac ® OFF mode, traction control and ESC are both enabled.

Regardless of the driver selected state of the AdvanceTrac feature, when the ignition is cycled from ON to OFF and back to ON, both the traction control and the ESC are reset to enabled.

MyKey ® Interaction 

Through the MyKey ® feature, the traction control function of the stability control system can be configured to be always on or to allow the driver to select the traction control function on or off.

When the traction control function is configured to be always on and a MyKey ® restricted key is in use, the IPC will ignore any requests made by the driver to disable the traction control function and will not send any traction control disable messages to the ABS module. Refer to the Owner's Literature.

Stability-Traction Control Indicator (Sliding Car Icon) 

Refer to Instrumentation, Message Center, and Warning Chimes .

Stability-Traction Control Disabled Indicator (Sliding Car OFF Icon) 

Refer to Instrumentation, Message Center, and Warning Chimes .