Subaru Legacy 2005 Service Manual page 1911

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 5 (+) — Chassis ground (
(B135) No. 6 (+) — Chassis ground (
2 CHECK INPUT VOLTAGE OF ECM.
1) Start the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 5 (+) — Chassis ground (
(B135) No. 6 (+) — 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
(E57) No. 5 — (B136) No. 16:
(E57) No. 3 — (B136) No. 35:
4 CHECK ECM GROUND HARNESS.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 1 (+) — Chassis ground (
(B137) No. 2 (+) — Chassis ground (
(B137) No. 3 (+) — Chassis ground (
BZ:DTC P0638 THROTTLE ACTUATOR CONTROL RANGE/PERFORMANCE
(BANK 1)
NOTE:
For diagnostic procedure, refer to DTC P2101. <Ref. to EN(H6DO)(diag)-239, DTC P2101 THROTTLE AC-
TUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
Check
Is the voltage 10 — 13 V?
−
):
−
):
Is the voltage 13 — 15 V?
−
):
−
):
Is the resistance less than 1
Ω?
Is the voltage less than 1 V?
−
):
−
):
−
):
EN(H6DO)(diag)-215
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the open or
ground short cir-
cuit of power sup-
ply circuit.
Go to step 3. Repair the open or
ground short cir-
cuit of power sup-
ply circuit.
Go to step 4. Repair the open
circuit of harness
between ECM and
electronic throttle
relay.
Repair the poor Further tighten the
contact in ECM engine ground ter-
connector. minal.
Replace the ECM
if defective. <Ref.
to FU(H6DO)-34,
Engine Control
Module (ECM).>
No