Stability Assist System: Notes

With the ignition switch in the START or RUN positions, the ABS module functions similarly to a conventional ABS by monitoring and comparing the rotational speed of each wheel. Wheel speeds are measured by the wheel speed sensor, which detects the magnetic field of the sensor ring as it passes the face of the active wheel speed sensor. When the ABS module detects an impending wheel lock, wheel spin or vehicle motion that is inconsistent with the driver commands, brake pressure is modulated to the appropriate brake caliper(s) and the PCM modulates engine torque. The ABS module triggers the HCU to open and close the appropriate solenoid valves and the PCM regulates fuel and spark to the cylinders. Once the affected wheel(s) return to the desired speed or the undesired vehicle motion stops, the ABS module returns the solenoid valves to their normal position, the PCM returns the fuel and spark to their normal operation and normal ABS brake operation is restored.