Subaru Impreza 2004 Service Manual page 163

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK INPUT SIGNAL FOR ECM.
1)Turn the ignition switch to ON.
2)Place the shift lever in neutral.
3)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 8 (+) — Chassis ground ( − − − − ):
2 CHECK INPUT SIGNAL FOR ECM.
1)Place the shift lever in a position except for
neutral.
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 NEUTRAL POSITION SWITCH.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from transmission
harness.
3)Place the shift lever in neutral.
4)Measure the resistance between transmis-
sion harness and connector terminals.
Connector & terminal
Model without driver's control center dif-
ferential
(T9) No. 1 — No. 3:
Model with driver's control center differ-
ential
(T9) No. 2 — No. 5:
5 CHECK NEUTRAL POSITION SWITCH.
1)Place the shift lever in a position except for
neutral.
2)Measure the resistance between transmis-
sion harness connector terminals.
Connector & terminal
Model without driver's control center dif-
ferential
(T9) No. 1 — No. 3:
Model with driver's control center differ-
ential
(T9) No. 2 — No. 5:
6 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 8 — Chassis ground:
Check
Is the voltage more than 10 V? Go to step 2.
Is the voltage less than 1 V?
Is there poor contact in ECM
connector?
Is the resistance more than 1
MΩ?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
EN(H4DOTC)(diag)-242
Yes
Go to step 4.
Go to step 3. Go to step 4.
Repair poor con- Contact your Sub-
tact in ECM con- aru distributor ser-
nector. vice.
Go to step 5. Repair short circuit
in transmission
harness or replace
neutral position
switch.
Go to step 6. Repair short circuit
in transmission
harness or replace
neutral position
switch.
Go to step 7. Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
No