Subaru Impreza 2003 Service Manual page 668

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Start the engine, and warm-up the engine.
2)Turn the ignition switch to OFF.
3)Turn the ignition switch to ON.
4)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground ( − − − − ):
2 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 chassis ground.
Connector & terminal
(B136) No. 15 — Chassis ground:
3 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the resistance of harness between
ECM and TCM connector.
Connector & terminal
(B136) No. 15 — (B55) No. 10:
Check
Is the voltage more than 3 V?
Is the resistance more than 1
MΩ?
Is the resistance less than 1
Ω?
EN(H4SO)-256
Yes
Repair poor con- Go to step 2.
tact in ECM con-
nector.
Go to step 3. Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
Repair poor con- Repair open circuit
tact in ECM or in harness
TCM connector. between ECM and
TCM connector.
No