Anti-Lock Brake System: Description

NOTE: For more information on brake system, see the BRAKE SYSTEM article.

NOTE: Self-diagnostic tests are written specifically for Chrysler's Diagnostic Readout Box (DRB). A generic scan tool may not be capable of performing all necessary test functions.

NOTE: Modulator assembly may also be known as Hydraulic Control Unit (HCU).

Bendix-4 Anti-Lock Brake System (ABS) is designed to prevent wheel lock-up during heavy braking at speeds more than 3 MPH. This allows operator to maintain steering control while stopping vehicle in shortest distance possible. Major components are master cylinder and booster, modulator and pump/motor assembly, 4 wheel speed sensors, and Controller Anti-Lock Brake (CAB). See Fig 1. ABS also includes 2 warning lights (Red BRAKE and Amber ANTI-LOCK).

ABS has a self-diagnostic system for trouble shooting and system malfunction warning. ABS uses hydraulic power assist for normal power-assisted braking and to provide a source of high-pressure hydraulic fluid during anti-lock braking. Pedal feel is similar to conventional vacuum-boosted brake system. If additional force is applied during anti-lock stop, or if brake pedal is released and re-applied rapidly, driver may notice a very hard pedal feel. This is due to isolation of master cylinder during ABS operation, as wheel brake pressure is fed from modulator assembly.

Fig 1: Locating ABS Components (Typical)

Courtesy of CHRYSLER CORP.