Antilock Brake System

GENERAL DESCRIPTION
The Anti-lock Brake System (ABS) works on all four wheels. A combination of wheel speed sensor and Electronic Hydraulic Control Unit (EHCU) can determine when a wheel is about to stop turning and adjust brake pressure to maintain best braking.
The circuit consists of EHCU (Electronic Hydraulic Control Unit), wheel speed sensor, G-sensor, stoplight switch or brake switch (w/cruise control), backup light switch, transmission switch-1, 2, indicator light and data link connector.
EHCU controls brake fluid pressure applied to front and rear wheels to prevent wheels from locking by using speed sensor and G-sensor signals.
Based on wheel speed signals from speed sensor, EHCU activates solenoid valves incorporated into the control unit to increase, maintain or decrease brake fluid pressure.

This system helps the driver maintain greater control of the vehicle under heavy braking conditions.

System Components
EHCU, four Wheel Speed Sensors, Warning Light, and G-sensor.


Normal And Anti-lock Braking
Under normal driving conditions, the Anti-lock Brake System functions the same as a standard power assisted brake system. However, with the detection of wheel lock-up, a slight bump or kick-back will be felt in the brake pedal. This pedal "bump" will be followed by a series of short pedal pulsations which occurs in rapid succession. The brake pedal pulsation will continue until there is no longer a need for the anti-lock function or until the vehicle is stopped. A slight ticking or popping noise may be heard during brake applications when the Anti-lock features is being used.
When the Anti-lock feature is being used, the brake pedal may rise even as the brakes are being applied. This is also normal. Maintaining a constant force on the pedal will provide the shortest stopping distance.


Acronyms and Abbreviations
Several acronyms and abbreviations are commonly used throughout this section:
Anti-lock Brake System (ABS)
Circuit (CKT)
Data Link Connector (DLC)
Electronic Hydraulic Control Unit (EHCU)
Front Left (FL)
Front Right (FR)
Generator (GEN)
Millivolts (MV)
Rear Left (RL)
Rear Right (RR)
Revolution per Second (RPS)
Volts DC (VDC)
Volts AC (VAC)
Warning Light (W/L)
Wheel Speed Sensor (WSS)