Subaru LEGACY 2004 Service Manual page 288

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ABS (DIAGNOSTICS)
Step
1 CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ABSCM&H/
U.
3) Turn the ignition switch to ON.
4) Measure the voltage between ABSCM&H/
U connector and chassis ground.
Connector & terminal
(B301) No. 13 (+) — Chassis ground (
2 CHECK GROUND CIRCUIT OF MOTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between
ABSCM&H/U connector and chassis ground.
Connector & terminal
(B301) No. 12 — Chassis ground:
3 CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Run the engine at idle.
2) Measure the voltage between ABSCM&H/
U connector and chassis ground.
Connector & terminal
(B301) No. 18 (+) — Chassis ground (
4 CHECK GROUND CIRCUIT OF ABSCM&H/U.
1) Turn the ignition switch to OFF.
2) Measure the resistance between
ABSCM&H/U connector and chassis ground.
Connector & terminal
(B301) No. 15 — Chassis ground:
5 CHECK MOTOR OPERATION.
Operate the ABS sequence control. <Ref. to
ABS-10, ABS Sequence Control.>
NOTE:
Use the diagnosis connector to operate the
ABS sequence control.
6 CHECK POOR CONTACT IN CONNECTOR.
Turn the ignition switch to OFF.
7 CHECK ABSCM&H/U.
1) Connect all the connectors.
2) Erase the memory.
3) Perform the inspection mode.
4) Read the DTC.
Check
Is the voltage 10 — 15 V?
−
):
Is the resistance less than 0.5
Ω?
Is the voltage 10 — 15 V?
−
):
Is the resistance less than 0.5
Ω?
Can the motor revolution noise
(buzz) be heard when carrying
out the ABS sequence control?
Is there poor contact in con-
nector between generator, bat-
tery and ABSCM&H/U?
Is the same DTC displayed?
ABS(diag)-72
Yes
Go to step 2. Repair the har-
ness connector
between battery
and ABSCM&H/U.
Go to step 3. Repair the
ABSCM&H/U
ground harness.
Go to step 4. Repair the har-
ness connector
between battery,
ignition switch and
ABSCM&H/U.
Go to step 5. Repair the
ABSCM&H/U
ground harness.
Go to step 6. Replace
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>
Repair the con- Go to step 7.
nector.
Replace Go to step 8.
ABSCM&H/U.
<Ref. to ABS-6,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>
No