Subaru Impreza 2003 Service Manual page 674

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK INPUT SIGNAL FOR ECM.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 18 (+) — Chassis ground ( − − − − ):
2 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 18 (+) — Chassis ground ( − − − − ):
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.
4 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connectors from ECM and
TCM.
3)Measure the resistance of harness between
ECM and TCM connector.
Connector & terminal
(B136) No. 18 — (B56) No. 14:
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 18 — Chassis ground:
6 CHECK POOR CONTACT.
Check poor contact in TCM connector.
Check
Is the voltage more than 4.5 V? Go to step 2.
Is the voltage more than 10 V? Repair battery
Is there poor contact in ECM
connector?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is there poor contact in TCM
connector?
EN(H4SO)-262
Yes
Go to step 4.
Go to step 3.
short circuit in har-
ness between
ECM and TCM
connector.
Repair poor con- Replace the ECM.
tact in ECM con- <Ref. to
nector. FU(H4SO)-48,
Engine Control
Module (ECM).>
Go to step 5. Repair open circuit
in harness
between ECM and
TCM connector.
Go to step 6. Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
Repair poor con- Replace the TCM.
tact in TCM con- <Ref. to 4AT-70,
nector. Transmission Con-
trol Module
(TCM).>
No