Subaru IMPREZA 2004 Service Manual page 426

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of throttle position sensor sig-
nal using Subaru Select Monitor or OBD-II
general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground while throttle valve is fully
closed.
Connector & terminal
(B135) No. 3 (+) — Chassis ground ( − − − − ):
3 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 3 (+) — Chassis ground ( − − − − ):
4 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 13 (+) — Chassis ground ( − − − − ):
5 CHECK INPUT SIGNAL FOR ECM. (USING
SUBARU SELECT MONITOR.)
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 13 (+) — Chassis ground ( − − − − ):
Check
Is the voltage less than 0.1 V? Go to step 2.
Is the voltage more than 4.5 V? Go to step 4.
Does the voltage change by
shaking the ECM harness and
connector?
Is the voltage more than 0.1 V? Go to step 6.
Does the voltage change by
shaking the ECM harness and
connector?
EN(H4SO)(diag)-117
ENGINE (DIAGNOSTICS)
Yes
Even if malfunction
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector may be the
cause.
NOTE:
In this case, repair
the following:
• Poor contact in
throttle position
sensor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Go to step 3.
Repair poor con- Contact with SUB-
tact in ECM con- ARU distributor
nector. service.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Go to step 5.
Repair poor con- Go to step 6.
tact in ECM con-
nector.
No
be-
probable
multiple