Subaru Forester 2004 Service Manual page 121

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTIC)
Step
1 CHECK SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and terminal.
Connector & terminal
(B136) No. 29 (+) — (B136) No. 35 (
3) Check the voltage change by shaking the
harness and connector of ECM, engine har-
ness connector and electronic throttle control
connector.
2 CHECK POOR CONTACT.
Check the poor contact in connector between
ECM and electronic throttle control.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connectors from the elec-
tronic throttle control.
4) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(B136) No. 16 — (E57) No. 5:
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 16 — Chassis ground:
(B136) No. 29 — Chassis ground:
5 CHECK SENSOR POWER SUPPLY.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 (+) — Engine ground (
4) Check the voltage change by shaking the
harness and connector of ECM and engine
harness connector while monitoring the value
with voltage meter.
6 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 4 — Engine ground:
Check
Is the voltage more than 0.8 V? Go to step 2.
−
):
Is there poor contact?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is the voltage 4.5 — 5.5 V?
−
):
Is the resistance more than 10
Ω?
EN(H4DOTC 2.5)-120
Yes
Go to step 3.
Repair the poor Temporary poor
contact. contact occurred,
but it is normal at
present.
Go to step 4. Repair the open
circuit of harness
connector.
Go to step 5. Repair the chas-
sis short circuit of
harness.
Go to step 6. Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.
Repair poor con- Repair the poor
tact of electronic contact in ECM
throttle control connector. Replace
connector. the ECM if defec-
Replace the elec- tive. <Ref. to
tronic throttle con- FU(H4DOTC 2.5)-
trol if defective. 41, Engine Con-
trol Module
(ECM).>
No