ABS MODULATOR VALVES

TM 9-2320-303-24-1

ANTI-LOCK BRAKE SYSTEM TROUBLESHOOTING AND TESTING - CONTINUED

0019 00

ABS MODULATOR VALVES - CONTINUED

NOTE

The valves will cycle in 1-2-3-4 order, then diagonally in 1-2 and 3-4 order.

Cab

Curbside

Fig 2. Modulator Valve Checking

ABS SENSORS

ABS sensor systems consist of a tooth wheel mounted on the hub of each monitored wheel and a sensor installed so that

its end is against the tooth wheel. The sensor continuously sends wheel speed information to the ECU. A sensor clip holds the

sensor in place at the tooth wheel.

The type of axle determines the sensor mounting location:

Steering axle sensors are installed in the steering knuckle or in a bolted-on bracket.

Drive axle sensors are mounted in a block attached to the axle housing or in a bolted-on bracket.

SYSTEM COMPONENTS

The ECU is the brain of the ABS system. It receives information from the sensors and sends signals to the ABS valves.

See Fig 1.

0019 00-4