Subaru IMPREZA 2004 Service Manual page 538

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ECM and
TCM.
3)Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B137) No. 19 — Chassis ground:
3 CHECK OUTPUT SIGNAL FOR ECM.
1)Connect the connector to ECM.
2)Turn the ignition switch to ON.
3)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 19 (+) — Chassis ground ( − − − − ):
4 CHECK DTC FOR AUTOMATIC TRANSMIS-
SION.
Read the DTC for automatic transmission.
<Ref. to 4AT(diag)-24, Read Diagnostic Trou-
ble Code (DTC).>
Check
Is the voltage less than 1 V?
Is the resistance more than 1
MΩ?
Is the voltage more than 5 V?
Does the DTC appear for auto-
matic transmission?
EN(H4SO)(diag)-229
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Even if malfunction
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time.
NOTE:
In this case, repair
the following:
• Poor contact in
ECM connector
• Poor contact in
TCM connector
Go to step 3. Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
Go to step 4. Repair poor con-
tact in ECM con-
nector.
Check DTC for Replace the TCM.
automatic trans- <Ref. to 4AT-74,
mission. <Ref. to Transmission Con-
4AT(diag)-40, trol Module
Diagnostic Proce- (TCM).>
dure with Diagnos-
tic Trouble Code
(DTC).>
No