Traction Assist

With the ignition switch in the RUN position, the ABS module monitors and compares the rotational speed of each wheel. Wheel speeds are measured by the wheel speed sensor, which electrically senses each tooth of the sensor tone ring as it passes through the magnetic field produced by the wheel speed sensor. When the ABS module detects an impending wheel spin that is inconsistent with the driver commands, brake pressure is modulated to the appropriate brake caliper(s). The ABS module triggers the HCU to open and close the appropriate solenoid valves. Once the affected wheel(s) return to the desired speed, the ABS module returns the solenoid valves to their normal position and normal base brake operation is restored.

The ABS module communicates with the PCM to assist with maintaining vehicle traction. At lower speeds, when the drive wheels lose traction and begin to spin, the ABS module requests the PCM to reduce engine torque while simultaneously applying and releasing the appropriate brake caliper(s) to maintain traction. The PCM accomplishes this by minor incremental timing changes and fewer fuel injector pulses until the ABS module ends the request. The request ends when the driven wheel speed returns to the desired speed. At higher speed, the traction control is accomplished only through the PCM torque control.