Subaru LEGACY 2003 Service Manual page 193

DIAGNOSTICS CHART WITH SELECT MONITOR
Step
1 CHECK HARNESS BETWEEN ECM AND VD-
CCM.
1) Turn ignition switch to OFF.
2) Disconnect connector from VDCCM and
ECM.
3) Measure resistance between VDCCM and
ECM.
Connector & terminal
H4 engine RHD without OBD model
(F87) No. 45 — (B134) No. 24:
H4 engine RHD with OBD model
(F87) No. 45 — (B134) No. 32:
H4 engine LHD model
(F87) No. 45 — (B134) No. 24:
H6 engine model
(F87) No. 45 — (B136) No. 12:
Is the measured value less than the speci-
fied value?
2 CHECK GROUND SHORT OF HARNESS.
Measure resistance between VDCCM and
ECM.
Connector & terminal
(F87) No. 45 — Chassis ground:
Does the measured value exceed the specified
value?
3 CHECK BATTERY SHORT OF HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between VDCCM and
chassis ground.
Connector & terminal
(F87) No. 45 ( + + + + ) — Chassis ground ( − − − − ):
Is the measured value less than the speci-
fied value?
4 CHECK INPUT VOLTAGE FROM ECM.
1) Turn ignition switch to OFF.
2) Connect connector to VDCCM.
3) Turn ignition switch to ON.
4) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
H4 engine RHD without OBD model
(B134) No. 24 (+) — Chassis ground ( − − − − ):
H4 engine RHD with OBD model
(B134) No. 32 (+) — Chassis ground ( − − − − ):
H4 engine LHD model
(B134) No. 24 (+) — Chassis ground ( − − − − ):
H6 engine model
(B136) No. 12 (+) — Chassis ground ( − − − − ):
Is the measured value within the specified
range?
5 CHECK POOR CONTACT IN ECM CONNEC-
TORS.
Is there poor contact in ECM connector?
6 ERASE MEMORY.
1) Connect all connectors.
2) Erase the memory.
Can the memory be erased?
Value
0.5 Ω
1 MΩ
0.5 V
10 — 15 V
There is poor contact.
Can be erased.
VDC-191
VDC (DIAGNOSTICS)
Yes
Go to step 2. Repair or replace
open circuit
between VDCCM
and ECM.
Go to step 3. Repair or replace
ground short cir-
cuit between
VDCCM and ECM.
Go to step 4. Repair or replace
battery short cir-
cuit between
VDCCM and ECM.
Go to step 6. Go to step 5.
Replace ECM. Repair or replace
<Ref. to ECM connector.
FU(H6DO)-46,
Engine Control
Module.>
Go to step 7. Replace VDCCM.
<Ref. to VDC-8,
VDC Control Mod-
ule (VDCCM).>
No