Fig. 10 Pump Motor Relay With Power Distribution

Center

Fig. 11 Pump Motor Relay W/O Power Distribution

Center

The (CAB) by itself, also has the ability to turn on the Amber Anti-Lock Warning Lamp. The (CAB) can turn on the Amber Anti-Lock Warning Lamp by providing a ground at pin 15.

ANTI-LOCK WARNING LAMP ON

System Relay and Anti-Lock Warning Lamp

Relay De-Energized.

When the Amber Anti-Lock Warning Lamp is on, there is no electrical current flow from the (CAB) at pin 57. The System Relay coil is NOT energized. No electrical current flows to pin 47 and 41 (modulator valve power), or to the Anti-Lock Warning Lamp Relay coil. Thus, the Amber Anti-Lock Warning Lamp is not energized. The Amber Anti-Lock Warning Lamp is grounded through the Anti-Lock Warning Lamp Relay contacts. The Amber Anti-Lock Warning Lamp is turned on.

HYDRAULIC CIRCUITS AND VALVE OPERATION

Through the following operation descriptions and diagrams. The function of the various hydraulic control valves in the ABS system will be described. The fluid control valves mentioned below, control the flow of pressurized brake fluid to the wheel brakes during the different modes of Anti-Lock braking.

For explanation purposes we will assume all speed sensors are sending the same wheel speed information, requiring the same hydraulic fluid modulation at the same rate.

NORMAL BRAKING

ISOLATION VALVES

Open to primary and secondary master cylinder fluid supply (Fig. 1).

BUILD/DECAY VALVES

Closed (Fig. 1).

The brake pedal is applied. The travel of the brake pedal closes primary and secondary circuits from the master cylinder fluid supply. Brake fluid from the primary and secondary circuits flows through the open isolation valves, through the build/decay valves to the wheel brakes.

ABS BRAKING-BUILD PRESSURE

ISOLATION VALVES

Closed, isolating wheel brakes from master cylinder primary and secondary fluid supply. Through open build valves (Fig. 2).

BUILD/DECAY VALVES

Open (Fig. 2).

ABS BRAKING-DECAY PRESSURE

ISOLATION VALVES

Closed, isolating the wheel brakes from the master cylinder primary and secondary fluid supplies (Fig. 3).