Antilock Brake System Description

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 data list 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.








CONSTRUCTION DIAGRAM

ABS Operation Sounds and Sensations
During normal operation, the ABS makes several sounds that may seem unusual at first:
- A whining sound is caused by the ABS hydraulic unit motor.
- When pressure is applied to the brake pedal, the pulsation of the pedal causes a scraping sound.
- When the brakes are applied firmly, the ABS operates, rapidly applying and releasing the brakes many times per second. This repeated application and release of braking forces can cause the suspension to make a thumping sound and the tires to squeak.

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.
Self check
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.