Subaru LEGACY 2004 Service Manual page 852

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
24 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connectors from electronic
throttle control.
4) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(B137) No. 5 — (E57) No. 2:
(B137) No. 4 — (E57) No. 1:
25 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 2 (+) — Engine ground (
(E57) No. 1 (+) — Engine ground (
26 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 2 — Engine ground:
(E57) No. 1 — Engine ground:
27 CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic
throttle control connector terminals.
Connector & terminal
(E57) No. 2 — (E57) No. 1:
28 CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 3 — Chassis ground:
29 CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic
throttle control terminals.
Terminals
No. 1 — No. 2:
30 CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and
fully closed positions with fingers.
Check that the valve returns to the specified
position when releasing fingers.
Check
Is the resistance less than 1
Ω?
Is the voltage less than 5 V?
−
):
−
):
Is the resistance more than 1
MΩ?
Is the resistance more than 1
MΩ?
Is the resistance less than 10
Ω?
Is the resistance less than 5
Ω?
Does the valve return to the
specified position?
Standard value: 3 mm (0.12 in)
from fully closed position
EN(H4SO 2.5)(diag)-236
Yes
Go to step 25. Repair the open
circuit of harness
connector.
Go to step 26. Repair power sup-
ply short circuit in
harness between
ECM and elec-
tronic throttle con-
trol.
Go to step 27. Repair the short
circuit of harness.
Go to step 28. Repair the short
circuit of harness.
Go to step 29. Repair the open
circuit of harness.
Go to step 30. Replace the elec-
tronic throttle con-
trol.
Repair the poor Replace the elec-
contact in ECM tronic throttle con-
connector. trol.
Replace the ECM
if defective. <Ref.
to FU(H4SO 2.5)-
36, Engine Con-
trol Module
(ECM).>
No