Traction Control Function

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 High Speed Controller Area Network (HS-CAN). The ABS  module also sends a traction event message to the IPC  over the High Speed Controller Area Network (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 the traction event message (gatewayed through the BCM  over the Medium Speed Controller Area Network (MS-CAN)), it flashes the stability/traction control indicator (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.

On vehicles equipped with a message center and steering wheel switches, the driver can disable the traction control function through the menu in the message center, refer to the Owner's Literature for instructions on disabling the traction control function. This is independent of the ABS  and Electronic Stability Control (ESC) functions, which cannot be disabled by the driver. When the driver disables the traction control function through the message center, the BCM  communicates traction control function status to the ABS  module via the High Speed Controller Area Network (HS-CAN). 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 traction control function is disabled if there is a wheel speed sensor or solenoid valve DTC  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 BCM  which gateways the message to the IPC  over the Medium Speed Controller Area Network (MS-CAN) to illuminate the sliding car icon.