Subaru IMPREZA GD 2007 Series Manual page 347

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 7 (+) — Chassis ground (–):
(B135) No. 2 (+) — Chassis ground (–):
2 CHECK INPUT VOLTAGE OF ECM.
1) Start the engine.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 7 (+) — Chassis ground (–):
(B135) No. 2 (+) — Chassis ground (–):
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM and electronic throttle control connector.
Connector & terminal
(B134) No. 19 — (E57) No. 5:
(B134) No. 29 — (E57) No. 3:
4 CHECK ECM GROUND HARNESS.
Measure the voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 5 (+) — Chassis ground (–):
(B137) No. 1 (+) — Chassis ground (–):
(B137) No. 2 (+) — Chassis ground (–):
(B137) No. 3 (+) — Chassis ground (–):
(B137) No. 7 (+) — Chassis ground (–):
CE:DTC P0638 THROTTLE ACTUATOR CONTROL RANGE/PERFORMANCE
(BANK 1)
NOTE:
For the diagnostic procedure, refer to DTC P2101. <Ref. to EN(H4SO)(diag)-286, DTC P2101 THROTTLE
ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
Check
Is the voltage 10 — 13 V?
Is the voltage 13 — 15 V?
Is the resistance less than 1 Ω? Go to step 4.
Is the voltage less than 1 V?
EN(H4SO)(diag)-238
Yes No
Go to step 2. Repair the open or
ground short circuit
of power supply
circuit.
Go to step 3. Repair the open or
ground short circuit
of power supply
circuit.
Repair the open
circuit of harness
between ECM and
electronic throttle
control connector.
Repair poor con- Repair the follow-
tact of the ECM ing item.
connector. • Retightening of
engine ground ter-
minals
• Poor contact of
coupling connector