Fault Code Guide

WARNING
Before working on or around hydraulic brake
systems and components, see Safety Precau-
tions 100. Failure to do so may result in personal
injury.
Voltage Check
NOTE: Along with the following, the voltage can
also be checked using the Meritor WABCO
TOOLBOX Software.
IMPORTANT: Voltage must be between 9.5 and
14 volts for the 12-volt hydraulic ABS to function
properly.
1. Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the rear tires to prevent vehicle movement.
2. Turn the ignition on.
3. Check the voltage between Pins 9 and 3, 9 and
2, and 9 and 11 on the black X2 ECU connector.
4. If voltage is not between 9.5 and 14 volts, verify
proper wiring connections. Make corrections as
required.
5. Remove the chocks from the rear tires.
ABS Indicator Light
IMPORTANT: If the ABS indicator light does not
come on after the ignition is turned on, check all
ABS fuses or circuit breakers and replace if
necessary. Check the wiring to the ABS indica-
tor light and repair or replace the wiring as re-
quired.
1. Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the rear tires to prevent vehicle movement.
2. Check the voltage potential at the light socket.
3. Check the continuity of the wires to the socket.
4. Replace the bulb.
5. Remove the chocks from the rear tires.
Sensor Voltage Output Test
IMPORTANT: Sensor output voltage must be at
least 0.2 volts AC at 30 rpm.
WARNING
Block the wheels to prevent the vehicle from
moving. Support the vehicle with safety stands.
Do not work under a vehicle supported only by
jacks. Jacks can slip and fall over. Serious per-
sonal injury can result.
1. Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the front and rear tires to prevent vehicle move-
ment.
2. Turn the ignition off.
3. To measure voltage at the pins on the sensor
connector, disconnect the sensor from the chas-
sis harness.
4. Raise the vehicle off of the ground. Put safety
stands under the axle.
5. Rotate the wheel by hand at 30 rpm (1/2 revolu-
tion per second).
6. Measure the voltage across the two pins at the
sensor connector.
7. If the voltage is not greater than 0.2 volts AC,
adjust the sensor and recheck. If the voltage is
still not greater than 0.2 volts AC, replace the
sensor.
8. Remove the safety stands and lower the vehicle.
9. Remove the chocks from the rear tires.
Sensor Resistance
IMPORTANT: The sensor resistance must be
between 500 and 2000 ohms. Measure resis-
tance at the sensor connector or at the pins on
the ECU connector.
1. Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the rear tires to prevent vehicle movement.
2. Turn the ignition off.
Meritor WABCO Hydraulic Antilock Braking System (ABS) 42.26
Component Tests
Business Class M2 Workshop Manual, Supplement 3, January 2002 140/1