Subaru 2002 IMPREZA Service Manual page 913

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK POWER SUPPLY TO IDLE AIR CON-
TROL SOLENOID VALVE.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from idle air con-
trol solenoid valve.
3)Turn the ignition switch to ON.
4)Measure the 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 the ignition switch to OFF.
2)Measure the 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 the connector from ECM.
2)Measure the resistance between ECM con-
nector 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 the ignition switch to ON.
2)Start the engine, and idle it.
3)Check the following items.
•Loose installation of intake manifold, idle air
control solenoid valve and throttle body
•Cracks of intake manifold gasket, idle air con-
trol solenoid valve gasket and throttle body
gasket
•Disconnections of vacuum hoses
Check
Is the voltage more than 10 V? Go to step 2.
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 connector?
Is the idling speed higher than
standard?
Is there a fault in the air intake
system?
EN(w/oOBD)-79
ENGINE (DIAGNOSTICS)
Yes
Repair the har-
ness and connec-
tor.
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 the har-
ness and connec-
tor.
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 the ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
Repair the poor Go to step 5.
contact in ECM
connector or idle
air control solenoid
valve connector.
Go to step 6. Go to step 8.
Repair the air suc- Go to step 7.
tion and leaks.
No