Hill Start Assist

The Anti-Lock Brake System (ABS) module uses the brake pedal switch message and Anti-Lock Brake System (ABS) wheel speed sensor input to determine that the vehicle is at a complete stop. The transmission selector lever message and parking brake message let the Anti-Lock Brake System (ABS) module know that the vehicle is not being parked. The stability sensor messages from the Restraints Control Module (RCM) enable the Anti-Lock Brake System (ABS) module to determine if the vehicle is on an incline greater than 5 degrees or greater than a 3% grade. The hill start assist function automatically engages once the above conditions have been met. As the driver releases the brake pedal, the Anti-Lock Brake System (ABS) module commands the Hydraulic Control Unit (HCU) to close the isolation valves which will maintain the current brake system pressure, preventing the vehicle from rolling down the incline. The Anti-Lock Brake System (ABS) will hold the brake pressure for up to 2 seconds while the driver transitions to the accelerator pedal. As the accelerator pedal is pressed and the engine Revolutions Per Minute (RPM) increases, the Anti-Lock Brake System (ABS) module gradually releases the brake pressure to make sure the vehicle is neither rolling back nor driving off until there is sufficient driving torque to accelerate the vehicle forward (or backward if reversing up the incline).