Anti-Lock Brake System/Vehicle Skid Control: Operation

Under normal driving conditions, ABS/VSC functions as a standard brake system. With detection of wheel lock-up, short pedal pulsations occurring in rapid succession will be felt in brake pedal. Pedal pulsation will continue until there is no longer a need for ABS function or until vehicle is stopped. Maintaining a constant force on the brake pedal provides shortest stopping distance.

A quick push on the brake pedal is interpreted by BA as emergency braking, and it supplements the braking power applied if driver has not stepped on the brake pedal hard enough. It measures the speed and force with which the brake pedal is pushed in order to determine if driver is attempting to brake rapidly, and applies additional pressure to maximize braking effort. When brake pedal pressure is reduced, system pressure also drops. The system is designed to be unnoticeable by the driver.

TRAC system automatically helps control spinning of drive wheels on slippery surfaces by reducing fuel to engine, then applying brake to spinning wheel if needed. It can be operated manually by pushing VSC OFF switch, located on instrument panel. VSC OFF indicator light will illuminate. Pushing switch a second time turns system back on. VSC OFF indicator light will go out. When traction control is applied, SLIP indicator light blinks when system is compensating for slipping wheel.

VSC uses steering angle and yaw rate sensors to determine if vehicle is experiencing oversteer or understeer tendencies. During a strong understeer condition, Skid Control ECU may reduce engine power output. It may also apply both front brakes and inside rear brake to redirect the vehicle in the proper direction. During a strong oversteer condition, Skid Control ECU may apply brake pressure to the front and rear outside wheels in order to reduce oversteer.