The ABS consists of components such as the wheel speed sensors, stoplight switch, hydraulic unit assembly (integrated with ABS-ECU), ABS rotor and the ABS warning light. If a problem occurs in the system, the malfunctioning components can be identified and the trouble symptoms will be memorized by the diagnostic function. In addition, reading of diagnostic trouble codes and actuator testing are possible by using the Scan Tool. If the ABS hydraulic unit is faulty, the ABS-ECU must be replaced. The ABS-ECU runs a self-check for 3 seconds upon start-up (also ignition switch ON, engine stopped). The ABS warning light should be illuminated during the self-check and turn off when the self-check completes.
ABS Operation Sounds And Sensations
During normal operation, the ABS makes several sounds that may seem unusual at first:
A pulse may be felt when the brake pedal is lightly pressed while driving at a low speed. This is a normal characteristic because the ABS system operation check is carried out when vehicle speed is 8 km/h (5 mph) or less.
Stopping Distances On Loose Road Surfaces
When braking on loose surfaces like snow-covered or gravel roads, steering control is maintained. The stopping distance may be longer for an ABS-equipped vehicle than the stopping distance for a vehicle with a conventional brake system.