Traction Control Function

The Anti-Lock Brake System (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 Anti-Lock Brake System (ABS) module modulates brake pressure to the appropriate brake caliper(s) by opening and closing the appropriate solenoid valves inside the Hydraulic Control Unit (HCU) while the hydraulic pump motor is activated. At the same time, the Anti-Lock Brake System (ABS) module sends a message over the High Speed Controller Area Network (HS-CAN) that a traction event is taking place. When the Powertrain Control Module (PCM) receives this message, it assists with traction control by adjusting engine timing and decreasing fuel injector pulses. When the Instrument Panel Cluster (IPC) receives this message, it flashes the stability/traction control indicator (sliding car icon). Once the driven wheel speed returns to the desired speed, the Anti-Lock Brake System (ABS) module returns the solenoid valves in the Hydraulic Control Unit (HCU) to their normal position, deactivates the hydraulic pump motor and sends another message over the High Speed Controller Area Network (HS-CAN) bus indicating that the event has ended. The Powertrain Control Module (PCM) returns engine timing and fuel injectors to normal operation and the Instrument Panel Cluster (IPC) extinguishes the sliding car icon. After the vehicle speed exceeds 100 kmh (62.1 mph), traction control is accomplished only through the Powertrain Control Module (PCM) torque control.

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 Anti-Lock Brake System (ABS), Electronic Stability Control (ESC) and Roll Stability Control (RSC) functions, which cannot be disabled by the driver. When the driver disables the traction control function through the message center, the Instrument Panel Cluster (IPC) communicates traction control system status to the Anti-Lock Brake System (ABS) module via the High Speed Controller Area Network (HS-CAN). The Anti-Lock Brake System (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 Anti-Lock Brake System (ABS) module disables the traction control function if there are any wheel speed sensor or solenoid valve Diagnostic Trouble Codes (DTCs) present in the Anti-Lock Brake System (ABS) module. The traction control function is also disabled if there is a communication error between the Anti-Lock Brake System (ABS) module and the Powertrain Control Module (PCM). When the traction control function is disabled, the Anti-Lock Brake System (ABS) module sends a message to the Instrument Panel Cluster (IPC) to illuminate the stability/traction control disabled indicator (sliding car OFF icon).