Subaru 2004 LEGACY Service Manual page 176

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
24 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 (
25 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:
26 CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic
throttle control connector terminals.
Connector & terminal
(E57) No. 2 — (E57) No. 1:
27 CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 3 — Chassis ground:
28 CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic
throttle control terminals.
Terminals
No. 1 — No. 2:
29 CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and
fully closed positions with fingers
Check the valve returns to the specified posi-
tion when releasing fingers.
Check
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(H6DO)(diag)-245
ENGINE (DIAGNOSTICS)
Yes
Go to step 25. Repair power sup-
ply short circuit in
harness between
ECM and elec-
tronic throttle con-
trol.
Go to step 26. Repair the short
circuit of harness.
Go to step 27. Repair the short
circuit of harness.
Go to step 28. Repair the open
circuit of harness.
Go to step 29. Repair the elec-
tronic throttle con-
trol.
Repair the poor Repair the elec-
contact in ECM tronic throttle con-
connector. trol.
Replace the ECM
if defective. <Ref.
to FU(H6DO)-34,
Engine Control
Module (ECM).>
No