Subaru LEGACY 2003 Service Manual page 76

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
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
#1; (B134) No. 20 — (E7) No. 3:
#2; (B134) No. 6 — (E7) No. 1:
#3; (B134) No. 19 — (E7) No. 6:
#4; (B134) No. 5 — (E7) No. 4:
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
#1; (B134) No. 20 — Chassis ground:
#2; (B134) No. 6 — Chassis ground:
#3; (B134) No. 19 — Chassis ground:
#4; (B134) No. 5 — 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?
5 CHECK SPECIFICATIONS.
Is the vehicle equipped with rear catalytic con-
verter?
6 CHECK IDLE SPEED.
Is idling speed within the specified value?
7 CHECK IDLE SPEED.
Is idling speed within the specified value?
Step
EN(H4SOw/oOBD)-74
Value
10 V
1 Ω
1 MΩ
There is poor contact.
Equipped with rear catalytic
converter.
550 — 750 rpm
600 — 800 rpm
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
(B22)
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
(B21)
Go to step 4. Repair ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
Repair poor con- Go to step 5.
tact in ECM con-
nector or idle air
control solenoid
valve connector.
Go to step 7. Go to step 6.
Go to step 8. Go to step 10.
Go to step 8. Go to step 10.
No