Subaru Legacy 2002 Service Manual page 892

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
1 CHECK POWER SUPPLY TO IDLE AIR
CONTROL 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 (−):
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:
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:
4 CHECK POOR CONTACT.
Check poor contact in ECM connector and
idle air control solenoid valve connector.
5 CHECK IDLE SPEED.
6 CHECK AIR INTAKE SYSTEM.
1) Turn ignition switch to ON.
2) Start engine, and idle it.
3) Check the following items.
¼ Loose installation of intake manifold, idle air
control solenoid valve and throttle body
¼ Cracks of intake manifold gasket, idle air
control solenoid valve gasket and throttle
body gasket
¼ Disconnections of vacuum hoses
Step
Is the voltage more than 10
V?
Is the resistance less than
1 Ω?
Is the resistance more than
1 MΩ?
Is there poor contact in
ECM connector or idle air
control solenoid valve con-
nector?
Is idling speed higher than
standard?
Is there a fault in air intake
system?
EN(w/oOBD)-81
Check Yes
Go to step 2.
Go to step 3.
Go to step 4.
Repair poor con-
tact in ECM con-
nector or idle air
control solenoid
valve connector.
Go to step 6.
Repair air suction
and leaks.
Engine (Diagnostics)
No
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
idle air control
solenoid valve
and main relay
connector
¼ Poor contact in
coupling connec-
tor (B22)
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
ECM and idle air
control solenoid
valve connector
¼ Poor contact in
coupling connec-
tor (B21)
Repair ground
short circuit in
harness between
ECM and idle air
control solenoid
valve connector.
Go to step 5.
Go to step 8.
Go to step 7.