Subaru Legacy 2002 Service Manual page 2728

DIAGNOSTICS CHART WITH SELECT MONITOR
No.
1 CHECK GROUND SHORT OF HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Disconnect connector (F91) from VDCH/U.
4) Measure resistance between VDCH/U con-
nector and chassis ground.
Connector & terminal
(F91) No. 13 — Chassis ground:
(F91) No. 14 — Chassis ground:
2 CHECK BATTERY SHORT OF HARNESS.
Measure voltage between VDCH/U connector
and chassis ground.
Connector & terminal
(F91) No. 13 (+) — Chassis ground (−):
(F91) No. 14 (+) — Chassis ground (−):
3 CHECK BATTERY SHORT OF HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between VDCH/U con-
nector and chassis ground.
Connector & terminal
(F91) No. 13 (+) — Chassis ground (−):
(F91) No. 14 (+) — Chassis ground (−):
4 CHECK INPUT VOLTAGE OF PRESSURE
SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM.
3) Remove cover from VDCCM. <Ref. to
VDC-17, REMOVE, VDCCM Connector
Cover.>
4) Connect connector to VDCCM.
5) Connect all connectors.
6) Turn ignition switch to ON.
7) Do not depress brake pedal.
8) Measure voltage between VDCCM connec-
tor terminals.
Connector & terminal
(F87) No. 77 (+) — No. 76 (−):
(F87) No. 36 (+) — No. 76 (−):
5 CHECK BRAKE FLUID LEAKAGE.
Inspect fluid leakage between brake master
cylinder and VDCH/U.
6 CHECK BRAKE MASTER CYLINDER.
Inspect brake master cylinder hydraulic pres-
sure. <Ref. to BR-38, OPERATION CHECK
(WITH GAUGES), INSPECTION, Brake
Booster.>
7 CHECK BRAKE PEDAL STROKE.
Measure the stroke between non-forced pedal
position and forced pedal position with 50 kg
(110 lb).
8 CHECK INPUT VOLTAGE OF PRESSURE
SENSOR.
1) Depress the brake pedal with 50 kg (110
lb).
2) Measure voltage between VDCCM connec-
tor terminals.
Connector & terminal
A (F87) No. 77 (+) — No. 76 (−):
B (F87) No. 36 (+) — No. 76 (−):
Step
Is the resistance more than
1 MΩ?
Is the voltage less than 0.5
V?
Is the voltage less than 0.5
V?
Is the voltage between 0.48
and 0.72 V?
Does brake fluid leak?
Is hydraulic pressure nor-
mal?
Is the stroke less than 95
mm (3.74 in)?
Is the voltage between A
and B less than 0.2 V?
VDC-269
Check Yes
Go to step 2.
Go to step 3.
Go to step 4.
Go to step 5.
Retighten or
replace.
Go to step 7.
Go to step 8.
Go to step 9.
VDC (Diagnostics)
No
Repair harness
between VDCH/U
and VDCCM.
Repair harness
between VDCH/U
and VDCCM.
Repair harness
between VDCH/U
and VDCCM.
Replace VDCH/U.
<Ref. to VDC-11,
Hydraulic Control
Unit (H/U).>
Go to step 6.
Replace master
cylinder.
Perform bleeding
from brake sys-
tem.
Replace VDCH/U.
<Ref. to VDC-11,
Hydraulic Control
Unit (H/U).>