System Overview

Fig. 1 Anti-lock Brake System.:

DESCRIPTION
The purpose of the anti-lock brake system, Fig. 1, is to prevent wheel lock-up under heavy braking conditions on virtually any road surface. When a wheel locking condition exists, the Pressure Modulator Valve (PMV) assembly isolates each wheel's hydraulic circuit, then begins modulation of fluid pressure according to wheel speed inputs to the Electronic Brake Control Module (EBCM) or Electronic Brake and Traction Control Module (EBTCM). The PMV is controlled by the EBCM.

Modulation occurs by means of three ABS modes: pressure hold, pressure reduce and pressure increase. The PMV assembly has two valves per individual hydraulic circuit. These valves work in pairs to achieve the three ABS modes. The ABS system isolates, monitors and controls all wheels simultaneously.