TM 9-2320-302-20
0013 00-3
ANTI-LOCK BRAKE SYSTEM TROUBLESHOOTING AND TESTING - CONTINUED
0013 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
A.
Cab
B.
Curbside
Figure 2. Modulator Valve Checking.
ABS SENSORS
1.
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.
2.
The type of axle determines the sensor mounting location:
a.
Steering axle sensors are installed in the steering knuckle or in a bolted-on bracket.
b.
Drive axle sensors are mounted in a block attached to the axle housing or in a bolted-on bracket.
SYSTEM COMPONENTS
1.
The ECU is the brain of the ABS system. It receives information from the sensors and sends signals to the ABS valves
(Figure 1).
2.
A tooth wheel (Figure 3) is mounted at the hub of each sensed wheel, with a sensor installed so that its end is against the
tooth wheel. A sensor clip holds the sensor in place at the tooth wheel. The sensor and clip must be greased with Rock-
well WABCO-recommended lubricant.
