Subaru Legacy 2002 Service Manual page 1462

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 10 (+) — Chassis ground
(−):
2 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 and engine ground.
Connector & terminal
(E7) No. 2 (+) — Engine ground (−):
3 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between
ECM and idle air control solenoid valve con-
nector.
Connector & terminal
(B136) No. 10 — (E7) No. 1:
4 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
Measure resistance of harness between ECM
and chassis ground.
Connector & terminal
(B136) No. 10 — Chassis ground:
5 CHECK GROUND CIRCUIT OF IDLE AIR
CONTROL SOLENOID VALVE.
Measure resistance of harness between idle
air control solenoid valve connector and
engine ground.
Connector & terminal
(E7) No. 3 — Engine ground:
6 CHECK POOR CONTACT.
Check poor contact in ECM and idle air con-
trol solenoid valve connectors.
Step
Is the voltage more than 3
V?
Is the voltage more than 10
V?
Is the resistance less than
1 Ω?
Is the resistance less than
10 Ω?
Is the resistance less than
5 Ω?
Is there poor contact in
ECM and idle air control
solenoid valve connectors?
EN(H6)-255
Check Yes
Repair poor con-
tact in ECM con-
nector.
Go to step 3.
Go to step 4.
Repair ground
short circuit in
harness between
ECM and idle air
control solenoid
valve connector.
Go to step 6.
Repair poor con-
tact in ECM and
idle air control
solenoid valve
connectors.
Engine (DIAGNOSTICS)
No
Go to step 2.
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
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
Go to step 5.
Repair open cir-
cuit in harness
between idle air
control solenoid
valve connector
and engine
ground terminal.
Replace idle air
control solenoid
valve. <Ref. to
FU(H6)-36, Idle
Air Control Sole-
noid Valve.>