Subaru 2002 IMPREZA Service Manual page 927

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
2 CHECK INPUT SIGNAL FOR ECM.
1)Lift-up the vehicle.
2)Set the positive (+) terminal and ground lead
of oscilloscope at ECM connector terminals.
Connector & terminal
(B135) No. 24 (+) — Chassis ground (–):
1)Start the engine.
2)Shift on the gear position, and put the vehicle
at constant speed.
3)Measure the signal voltage indicated on
oscilloscope.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.
4 CHECK HARNESS BETWEEN ECM AND
COMBINATION METER CONNECTOR.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B135) No. 24 (+) — Chassis ground ( − − − − ):
5 CHECK HARNESS BETWEEN ECM AND
COMBINATION METER CONNECTOR.
1)Turn the ignition switch to OFF.
2)Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B135) No. 24 — Chassis ground:
6 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Check
Is the voltage more than 3 V?
Is there poor contact in ECM
connector?
Is the voltage more than 2 V?
Is the resistance less than 10
Ω?
Is there poor contact in ECM
connector?
EN(w/oOBD)-93
ENGINE (DIAGNOSTICS)
Yes
Go to step 3. Go to step 4.
Repair the poor Replace the ECM.
contact in ECM. <Ref. to FU(w/
oOBD)-48, Engine
Control Module.>
Repair the har- Go to step 5.
ness and connec-
tor.
NOTE:
In this case, repair
the following:
Battery short cir-
cuit in harness
between ECM and
combination meter
connector
Repair the ground Go to step 6.
short circuit in har-
ness between
ECM and combi-
nation meter con-
nector.
Repair the poor Replace the ECM.
contact in ECM. <Ref. to FU(w/
oOBD)-48, Engine
Control Module.>
No