This section covers the physical and operational descriptions, and the on-car service procedures for the Mark 20e Antilock Brake System (ABS) and Mark 20e Antilock Brake System with traction control. 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.
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-Speed Traction Control
The traction control system reduces wheel slip and maintains traction at the driving speeds below 64 km/h (40 mph) when road conditions call for traction assistance. This system shares most base brake hardware used on vehicles without ABS. A vehicle equipped with ABS, however, uses a different master cylinder and brake tubes. Also included in the ABS system is an integrated control unit (ICU) and four wheel speed sensors. These components are described in detail in this section. All vehicles with ABS come standard with four-wheel-disc brakes.