Service manual

TC Series Hydraulic Brake ABS System
030.1-18
Ignition Key On to determine
ABS blink code fault
Ignition Key off to test system (except where noted)
1 2 3 4 5
Fault
Code
Problem Area Connector Pins to be
Tested
Correct Volt Ohm
Meter Reading
Action
7-7 Recalculation pump
does not switch off.
OR
Recirculation pump
does not switch on (low
level with act.)
18-pin 8 and 12
8 and 12
0 volt
Turn Ignition on
12 volts DC
Check the recirculation
pump wiring, the pump
relay, fuse and pump
connections. Repair or
replace as needed.
7-8 Recirculating pump
motor locked.
18-pin Link pins
2 and 8
Turn Ignition on Excessive current
failure. If pump does
not run when pins are
linked, replace
modulator assembly.
8-1 No voltage 18-pin 1 and 2 Turn Ignition on
12 volts DC
Check the valve relay,
fuse, and wiring.
Repair or replace as
needed.
8-2 Continuous supply to
ECU with ignition off.
18-pin 5 and 12 0 volt Check for proper wiring
connections. Make
necessary repairs.
8-3 Internal ECU fault --- --- --- Replaced ECU
Table 3—D Version Hydraulic ABS Blink Codes (continued)
Testing the System
TO PREVENT SERIOUS EYE INJURY,
ALWAYS WEAR EYE PROTECTION
WHEN PERFORMING VEHICLE
MAINTENANCE OR SERVICE.
EXHAUST GAS CONTAINS POISON.
WHEN TESTING A VEHICLE WITH THE
ENGINE RUNNING, TEST IN A WELL-
VENTILATED AREA.
TO AVOID SERIOUS PERSONAL
INJURY, KEEP AWAY, AND KEEP TEST
EQUIPMENT AWAY, FROM ALL
MOVING OR HOT ENGINE PARTS.
•
Reference and observe the vehicle
manufacturer’s Warning, Cautions, and
Service Procedures.
•
When testing, set the parking brake and place
the gear selector in NEUTRAL (manual
transmission) or PARK (automatic
transmission) unless otherwise directed.
Test Equipment Volt-Ohm Meter (VOM)
Use of a VOM with automatic polarity sensing is
recommended. This eliminates the concern of the
polarity of the meter leads during voltage
measurements.
System Requirements and Component Tests
•
Tire Size Range
For proper hydraulic ABS operation, front and rear
tire sizes must be within 16% of each other.
Contact the Meritor WABCO Customer Support
Center at [phone] if you plan a tire size
difference of more than 8%.
Calculate the tire size with the following equation:
RPM Steer
% Difference = { ————— – 1} x 100
RPM Drive
RPM = Tire Revolutions Per Mile
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