Subaru Legacy 2003 Service Manual page 684

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK POWER SUPPLY TO IDLE AIR CON-
TROL SOLENOID VALVE.
1) Turn ignition switch to OFF.
2) Disconnect connector from idle air control
solenoid valve.
3) Turn ignition switch to ON.
4) Measure voltage between idle air control
solenoid valve connector and engine
ground.
Connector & terminal
(E7) No. 2 (+) — Engine ground ( − − − − ):
(E7) No. 5 (+) — Engine ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
2 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between ECM and idle
air control solenoid valve connector.
Connector & terminal
DTC P1510; (B134) No. 20 — (E7) No. 4:
DTC P1512; (B134) No. 6 — (E7) No. 1:
DTC P1514; (B134) No. 5 — (E7) No. 6:
DTC P1516; (B134) No. 19 — (E7) No. 3:
Is the measured value less than the speci-
fied value?
3 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Disconnect connector from ECM.
2) Measure resistance between ECM connec-
tor and chassis ground.
Connector & terminal
DTC P1510; (B134) No. 20 — Chassis
ground:
DTC P1512; (B134) No. 6 — Chassis
ground:
DTC P1514; (B134) No. 5 — Chassis
ground:
DTC P1516; (B134) No. 19 — Chassis
ground:
Does the measured value exceed the spec-
ified value?
4 CHECK POOR CONTACT.
Check poor contact in ECM connector and idle
air control solenoid valve connector.
Is there poor contact in ECM connector or idle
air control solenoid valve connector?
Value
10 V
1 Ω
1 MΩ
There is poor contact.
EN(H4SO)-287
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
idle air control
solenoid valve and
main relay con-
nector
• Poor contact in
coupling connector
Go to step 3. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and idle air
control solenoid
valve connector
• Poor contact in
coupling connector
Repair ground Go to step 4.
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
Repair poor con- Replace idle air
tact in ECM con- control solenoid
nector or idle air valve. <Ref. to
control solenoid FU(H4SO)-34, Idle
valve connector. Air Control Sole-
noid Valve.>
No