Subaru Impreza 2003 Service Manual page 1427

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK INPUT SIGNAL FOR ECM.
1)Turn the ignition switch to ON.
2)Set the shift lever to except neutral position.
3)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 8 (+) — Chassis ground ( − − − − ):
2 CHECK INPUT SIGNAL FOR ECM.
1)Set the shift lever to neutral position.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 8 (+) — Chassis ground ( − − − − ):
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.
4 CHECK INPUT SIGNAL FOR ECM.
1)Disconnect ECM connector from ECM.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 8 (+) — Chassis ground ( − − − − ):
5 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connectors from ECM and
transmission harness connector (T9).
3)Measure the resistance of harness between
ECM and neutral switch connector.
Connector & terminal
(B134) No. 8 — (B128) No. 1:
6 CHECK NEUTRAL POSITION SWITCH
GROUND LINE.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 3 — Engine ground:
7 CHECK NEUTRAL POSITION SWITCH.
1)Set the shift lever to except neutral position.
2)Measure the resistance between transmis-
sion harness connector receptacle's terminals.
Terminals
No. 1 — No. 3:
8 CHECK POOR CONTACT.
Check poor contact in the transmission har-
ness connector.
Check
Is the voltage less than 1 V?
Is the voltage more than 10 V? Go to step 3.
Is there poor contact in ECM
connector?
Is the voltage more than 10 V? Repair the battery
Is the resistance less than 1
Ω?
Is the resistance less than 5
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in the
transmission harness connec-
tor?
EN(H4DOTC)-251
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Go to step 4.
Go to step 4.
Repair the poor Contact your Sub-
contact in ECM aru distributor ser-
connector. vice.
Go to step 5.
short circuit in har-
ness between
ECM and trans-
mission connector.
Go to step 6. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and trans-
mission harness
• Poor contact in
transmission har-
ness connector
• Poor contact in
ECM connector
Go to step 7. Repair the open
circuit in harness
of neutral position
switch ground line.
Go to step 8. Replace the neu-
tral position
switch.
Repair poor con- Contact your Sub-
tact in transmis- aru distributor ser-
sion harness vice.
connector.
No