Brakes - Description

DESCRIPTION

NOTE: The Electronic Stability Control (ESC) may also be referred to as Electronic Stability Program (ESP) depending on the vehicle model year and configuration. Certain components may also reference ESP, ESC, or use the traction control symbol.

ANTILOCK BRAKE SYSTEM WITH ELECTRONIC STABILITY CONTROL





This vehicle uses the Continental Mk25e electronic brake control system. The system includes ABS (Anti-lock Brake System), EVBP (Electronic Variable Brake Proportioning), TCS (Traction Control System), BAS (Brake Assist System) and ESC (Electronic Stability Control). These system work together to enhance vehicle stability and control in various driving conditions and are commonly referred to as ESC. ESC is standard on this vehicle.

This electronic brake control system uses the following components to operate:

- Integrated Control Unit (ICU) - Hydraulic Control Unit (HCU) (2) and Antilock Brake Module (ABM) (1)
- Wheel Speed Sensors (WSS) - Four sensors (one sensor at each wheel)

- Dynamics Sensor - The Dynamics Sensor includes the Yaw Rate Sensor and the lateral Acceleration Sensor.
- Steering Angle Sensor (SAS) - The steering angle sensor is located in the Steering Column Control Module (SCCM) mounted on the steering column.
- Brake Pressure Sensor - The brake pressure sensor is located in the HCU and is not serviceable separate from the HCU.

ABS

The purpose of the Antilock Brake System (ABS) is to prevent wheel lockup under braking conditions on virtually any type of road surface. Antilock braking is desirable because a vehicle that is stopped without locking the wheels retains directional stability and some steering capability. This allows the driver to retain greater control of the vehicle during braking.

All vehicles equipped with ABS use Electronic Variable Brake Proportioning (EVBP) to balance front-to-rear braking when the brakes are applied in the partial braking range. For more information on electronic brake distribution, Brakes - Description.

ALL-SPEED TRACTION CONTROL





The traction control system (TCS) is an all-speed traction control. All-Speed Traction Control enhances mobility and prevents wheel slip when accelerating on slippery surfaces. It also provides a measure of directional stability control. Using the wheel-speed sensors, it can detect excessive yaw and help keep the car on the intended course, as for instance, when accelerating around a curve.

All-Speed Traction Control is effective up to 85 mph (137 km/h).

The traction control system may be turned off or on by depressing the ESC Off switch button (2) located in the instrument panel switch pod (1) located in center of the instrument panel.

ELECTRONIC STABILITY CONTROL

The Electronic Stability Program (ESC) enhances control and stability of the vehicle under various driving conditions. ESC corrects for over/under steering of the vehicle by applying the brake of the appropriate wheel to assist in counteracting the over/under steer condition. Engine power may also be reduced to help the vehicle maintain the desired path. ESC uses sensors in the vehicle to determine the vehicle path intended by the driver and compares it to the actual path of the vehicle. When the actual path does not match the intended path, ESC applies the brake of the appropriate wheel to assist in counteracting the oversteer or understeer condition.

- Oversteer - When the vehicle is turning more that appropriate for the steering wheel position.
- Understeer - When the vehicle is turning less than appropriate for the steering wheel position.

The "ESC/TCS" indicator light located in the instrument cluster starts to flash as soon as the tires lose traction and the ESC system becomes active. The "ESC/TCS" indicator light also flashes when the TCS is active.

The ESC(R) default mode is Full-On with every key-on. Pressing the ESC Off button once activates what is referred to as Partial mode. In Partial mode, Traction Control is deactivated and ESC(R) operates at a higher threshold, therefore, it will not come on as aggressively as in the Full-On mode. The system can be returned to "normal" Full-On mode by pressing and releasing the ESC Off switch. The ESC function lamp is illuminated in the cluster whenever the ESC system is turned off.

BRAKE ASSIST SYSTEM

The Brake Assist System (BAS) is designed to optimize the vehicle's braking capability during emergency braking maneuvers. The system detects an emergency braking situation by sensing the rate and amount of brake application and then applies optimum pressure to the brakes. This can help reduce braking distances. The BAS complements the antilock brake system (ABS). Applying the brakes very quickly results in the best BAS assistance.

ELECTRONIC VARIABLE BRAKE PROPORTIONING

Electronic Variable Brake Proportioning (EVBP) is used to balance front-to-rear braking in place of a traditional rear proportioning valve. The EVBP system uses the ABS system to control the slip of the rear wheels in partial braking range. The braking force of the rear wheels is controlled electronically by using the inlet and outlet valves located in the integrated control unit (ICU).

EVBP activation is nearly invisible to the customer since there is no pump motor noise and minimal brake pedal feedback.