Fault Code Guide

4. The resistance in each solenoid coil and cable
circuit must be 4 to 8 ohms.
• If the resistance in each solenoid circuit is
4 to 8 ohms, the cable and modulator
valve are good. Install the connector on
the ECU and remove the chocks from the
tires.
• If the resistance in either solenoid circuit is
less than 4 ohms or greater than 8 ohms,
go to the next test, "Modulator Valve Re-
sistance."
Modulator Valve Resistance
To check the resistance in the solenoid coils in an
ABS modulator valve, perform the following test:
1. Park the vehicle on a level surface, set the park-
ing brake, and shut down the engine. Chock the
rear tires.
2. Disconnect the cable connector from the modula-
tor valve being tested. See Table 1.
3. Connect ohmmeter probes to the modulator
valve "In" solenoid and "Ground" terminals and
read the resistance. Then, move the probes to
the "Out" and "Ground" terminals and read the
resistance. See Fig. 3 for the modulator terminal
locations.
4. The resistance in each solenoid coil must be 4 to
8 ohms.
• If the resistance in each solenoid coil is 4
to 8 ohms but the resistance noted in the
previous test, "Modulator Valve and Cable
Resistance" was not, repair or replace the
chassis harness.
• If the resistance is less than 4 ohms or
greater than 8 ohms, clean the terminals
on the modulator valve and check the re-
sistance again.
• If the resistance is still not correct, replace
the valve. See Subject 130 for instruc-
tions.
5. Install the cable connectors and remove the
chocks from the tires.
ATC Valve Tests
ATC Valve and Cable Resistance
To check the resistance in the ATC valve and cable
circuit, perform the following test:
1. Park the vehicle on a level surface, set the park-
ing brake, and shut down the engine. Chock the
rear tires.
2. Disconnect the ATC valve connector (X3) from
the ABS ECU. See Table 1.
3. Connect ohmmeter probes to the cable connec-
tor pins 5 and 6 for the ATC valve and read the
resistance.
4. The resistance in the ATC solenoid coil and
cable circuit must be 6.4 to 12 ohms.
• If the resistance is 6.4 to 12 ohms, the
ATC valve and cable are good. Install the
cable connector on the ECU and remove
the chocks from the tires.
• If the resistance is less than 6.4 ohms or
greater than 12 ohms go to the next test,
"ATC Valve Resistance."
ATC Valve Resistance
To check the resistance in the solenoid coil in the
ATC valve, perform the following test:
1. Park the vehicle on a level surface, set the park-
ing brake, and shut down the engine. Chock the
rear tires.
08/30/99
A
B
f430143
1
2
3
A. Delivery Port B. Supply Port
1. Ground (Common)
2. Exhaust Solenoid (Out)
3. Supply Solenoid (In)
Fig. 3, Modulator Valve Terminals
Meritor WABCO Pneumatic Antilock Braking System
(ABS)
42.00
Testing
Business Class M2 Workshop Manual, Supplement 0, January 2002 170/5