Subaru 2009 IMPREZA Service Manual page 700

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 31 and
No. 32 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 29 — No. 30:
2 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.
Connector & terminal
(B220) No. 29 (+) — Chassis ground (–):
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Disconnect the connectors from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B220) No. 32 (+) — Chassis ground (–):
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B220) No. 32 — Chassis ground:
(B220) No. 30 — Chassis ground:
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
Measure the resistance between ECM and
electronic throttle control relay connector.
Connector & terminal
(B136) No. 21 — (B220) No. 32:
(B136) No. 1 — (B220) No. 30:
6 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from electronic
throttle control.
3) Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 6:
(B134) No. 28 — Chassis ground:
Check
Is the resistance less than 1 ? Go to step 2.
Is the voltage 10 V or more?
Is the voltage 10 V or more?
Is the resistance 1 M or
more?
Is the resistance less than 1 ? Go to step 6.
Is the resistance 1 M or
more?
EN(H4SO)(diag)-283
ENGINE (DIAGNOSTICS)
Yes No
Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(H4SO)-50,
Electronic Throttle
Control Relay.>
Go to step 3. Repair the open or
ground short circuit
of power supply
circuit.
Repair the short Go to step 4.
circuit to power in
the harness
between ECM and
electronic throttle
control relay con-
nector.
Go to step 5. Repair the short
circuit in harness
to ground between
ECM and elec-
tronic throttle con-
trol relay
connector.
Repair the open
circuit in harness
between ECM and
electronic throttle
control relay con-
nector.
Go to step 7. Repair the short
circuit to ground in
harness between
ECM and elec-
tronic throttle con-
trol connector.