Subaru Impreza 2004 Service Manual page 183

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
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(H4DOTC)(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 HARNESS BETWEEN TUMBLE
GENERATOR VALVE POSITION SENSOR
AND ECM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from throttle posi-
tion sensor.
3)Measure the resistance of harness between
throttle position sensor connector and engine
ground.
Connector & terminal
(E50) No. 2 — Engine ground:
3 CHECK HARNESS BETWEEN THROTTLE
POSITION SENSOR AND ECM CONNEC-
TOR.
1)Turn the ignition switch to ON.
2)Measure the voltage between throttle posi-
tion sensor connector and engine ground.
Connector & terminal
(E50) No. 3 (+) — Engine ground ( − − − − ):
Check
Is the voltage more than 4.9 V? Go to step 2.
Is the resistance less than 5
Ω?
Is the voltage more than 4.9 V? Repair the battery
EN(H4DOTC)(diag)-262
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
tumble generator
valve position sen-
sor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Go to step 3. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
• Poor contact in
coupling connector
• Poor contact in
joint connector
Replace the tum-
short circuit in har- ble generator valve
ness between tum- assembly. <Ref. to
ble generator valve FU(H4DOTC)-41,
position sensor Tumble Generator
and ECM connec- Valve Assembly.>
tor. After repair,
replace the ECM.
<Ref. to
FU(H4DOTC)-49,
Engine Control
Module (ECM).>
No