Anti-Lock Brake System: Operation

Under normal driving conditions, the anti-lock brake system functions as a standard brake system. When vehicle speed reaches 3.8 MPH, the ABS system will diagnose pump motor by briefly operating motor. Pump motor operation may be heard inside vehicle.

The Electronic Control Unit (ECU) controls ABS by detecting speed sensor signals and activating solenoid valve in hydraulic unit. Control unit also controls pump motor and self-diagnostic function. If a problem in the ABS system is detected, ABS system functions as a conventional brake system. The ANTI-LOCK brake warning light will also come on.

With detection of wheel lock-up, short pedal pulsations, occurring in rapid succession, will be felt in brake pedal and steering wheel. Vehicle body may also vibrate slightly. These conditions are normal. Pedal pulsation will continue until there is no longer a need for anti-lock function or until vehicle is stopped.