General

Based on the traction control module's programming, the rear brakes are pulsed to slow a spinning wheel to restore traction or stability. This is carried out with two different methods depending on the system, model and year.

The first traction control system used a separate hydraulic unit that was installed between the brake master cylinder and the rear brakes. The traction control module regulated the solenoids in the hydraulic unit to carry out the brake regulation.

The Teves system and Bosch system starting with ASC/5 use the same hydraulic unit for both ABS and ASC regulation. Each wheel brake gets an inlet and outlet solenoid to control the brake fluid during traction control regulation.

All rear braking control uses the three phases of regulation as follows:

^ Pressure build-up - to apply brake pressure to slow the spinning wheel.
^ Pressure hold - to maintain the braking pressure at the wheel.
^ Pressure drop - allows the wheel to rotate again.