ABS with AdvanceTrac(R) and Roll Stability Control (RSC(R))

Anti-Lock Control

ABS

The ABS consists of the following components:

- ABS module- attached to the Hydraulic Control Unit (HCU), but can be serviced separately.

- Front wheel speed sensors- one sensor is located in each front wheel knuckle. The sensors are serviced separately from the knuckle.

- Front wheel speed sensor tone rings- one tone ring is located in each wheel bearing and wheel hub assembly and is serviced with the wheel bearing and wheel hub.

- HCU (Hydraulic Control Unit)- which contains several valves (inlet and outlet), the hydraulic pump motor and is mounted behind the battery and battery tray.

- Rear wheel speed sensors- one sensor is located in each rear wheel knuckle. The sensors are serviced separately from the knuckle.

- Rear wheel speed sensor tone rings- one tone ring is located in each wheel bearing and wheel hub assembly and is serviced with the wheel bearing and wheel hub.

ABS aids in the prevention of wheel lock-up during braking events which allows the driver to maintain steering control and stop in the shortest distance possible under most conditions. This is accomplished by the ABS module and HCU (Hydraulic Control Unit) modulating brake fluid pressure to the affected brake caliper(s) and wheel cylinder(s).

When the ABS activates, the driver may notice the following operational symptoms:

- A rumble or grinding sound may be heard (HCU (Hydraulic Control Unit) pump motor)

- If the driver's foot is on the brake pedal, a vibration may be felt in the brake pedal (HCU (Hydraulic Control Unit) pump motor and valves)

Electronic Brake Distribution (EBD)

The ABS module and HCU (Hydraulic Control Unit) incorporate a strategy called Electronic Brake Distribution (EBD). The EBD (Electronic Brake Distribution) strategy uses the HCU (Hydraulic Control Unit) as an electronic proportioning valve to create a balanced braking condition between the front and rear wheels and minimize the chance of rear wheel lockup during hard braking. A slight bump may be felt in the brake pedal when the EBD (Electronic Brake Distribution) adjusts the front to rear proportioning during a braking event.

ABS with AdvanceTrac(R) and Roll Stability Control (RSC(R))

The ABS with AdvanceTrac(R) and Roll Stability Control (RSC(R)) system consists of the same components as the conventional ABS above with the following additional components:

- Stability control sensors- located inside the Restraints Control Module (RCM) and consist of the following sensors: yaw rate, roll rate, lateral accelerometer, and longitudinal accelerometer. The sensors are integral to the RCM (Restraints Control Module) and cannot be serviced separately.

- Steering Angle Sensor Module (SASM)- vehicles that are equipped with Electronic Power Assist Steering (EPAS), but without the Active Park Assist feature have a SASM (Steering Angle Sensor Module) which does not have any electrical components inside. It is only installed to provide structural support for the clockspring and for turn signal canceling. On these vehicles, the steering wheel rotation and angle information (an input for RSC(R) (Roll Stability Control), Trailer Sway Control and Active Park Assist functions) is sent from the Power Steering Control Module (PSCM). Vehicles with the Active Park Assist feature have a fully functional SASM (Steering Angle Sensor Module) and receive steering wheel information from the SASM (Steering Angle Sensor Module).

- Steering wheel rotation sensor, vehicles with Hydraulic Power Assist Steering (HPAS) only- located on the RH side of the clockspring and is serviced separately from the clockspring assembly. The sensor provides steering rotation information to facilitate RSC(R) (Roll Stability Control) and Trailer Sway Control functions.

- Steering wheel rotation sensor ring, vehicles with HPAS (Hydraulic Power Assist Steering) only- located on the clockspring and is serviced with the clockspring assembly.

- Traction control switch- located in the instrument panel finish panel and is serviced separately from the finish panel.

The AdvanceTrac(R) with RSC(R) (Roll Stability Control) system is made up of the following 3 distinct vehicle systems:

- Traction Control System- helps to avoid excessive drive-wheel spin and loss of traction.

- Electronic Stability Control (ESC)- helps to avoid skids and lateral slides.

- RSC(R) (Roll Stability Control)- helps to avoid vehicle roll-over.

Traction Control System

The traction control system aids in the prevention of excessive wheel spin which allows the vehicle to maintain traction during acceleration. This is accomplished in the same manner as anti-lock braking but also includes the use of the PCM for modulating engine torque.

ESC (Electronic Stability Control) and RSC(R) (Roll Stability Control) Systems

Both systems constantly monitor vehicle direction of travel relative to the driver's intended course and aid in keeping the vehicle traveling along that course. The RSC(R) (Roll Stability Control) system also monitors the vehicle roll motion and aids in keeping the vehicle stable during sudden or abrupt maneuvers. This is accomplished in the same manner as anti-lock braking and traction control.

When any of the above 3 systems activate, the driver may notice the same operational symptoms as ABS along with the following additional symptoms:

- A small deceleration or a reduction in the acceleration of the vehicle (PCM modulating engine torque)

- The stability/traction control indicator (also known as the sliding car icon) flashes (indicating a traction or stability event is taking place)

Traction Control Switch

The traction control switch can be used by the driver to disable and enable the traction control system. When the switch is pressed, traction control is disabled. When the system is disabled, the stability/traction control indicator (sliding-car Off icon) in the Instrument Cluster (IC) (or message center if equipped) illuminates. The standard anti-lock control system cannot be disabled through the use of the traction control switch.

Trailer Sway Control

Trailer sway control is a unique function in the AdvanceTrac(R) with RSC(R) (Roll Stability Control) system that recognizes and aid in reducing trailer sway. The trailer sway control system continually monitors the steering wheel rotation sensor and the yaw rate sensor to identify specific, increasing yaw oscillations that occur during a trailer sway event. If the trailer sway event exceeds certain, programmed parameters, the ABS module and the HCU (Hydraulic Control Unit) modulates brake fluid pressure to specific brake caliper(s) and the PCM modulates engine torque until the trailer sway is reduced below the programmed parameters.

When the trailer sway control system activates, the vehicle produces the same noticeable symptoms as it does when the traction control and ESC (Electronic Stability Control) systems activate. In addition, the message center displays TRAILER SWAY, REDUCE SPEED.

The trailer sway control system only activates when the vehicle speed exceeds 50 km/h (31 mph). The system can be disabled during any key cycle. Refer to the Owner's Literature for information on disabling the system. The system is re-enabled when the ignition cycles from RUN to OFF and back to RUN.