Subaru Legacy 2004 Service Manual page 536

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main throttle sensor signal
using Subaru Select Monitor.
2 CHECK POOR CONTACT.
Check 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 electronic
throttle control.
4) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(B137) No. 23 — (E78) No. 5:
(B136) No. 18 — (E78) No. 1:
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Connect the ECM connector.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E78) No. 1 — Engine ground:
5 CHECK SENSOR OUTPUT POWER SUP-
PLY.
Measure the voltage between electronic throt-
tle control connector and engine ground.
Connector & terminal
(E78) No. 5 (+) — Engine ground (
6 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B137) No. 23 — (B136) No. 17:
Check
Is the voltage less than 4.63
V?
Is there poor contact in con-
nector between ECM and elec-
tronic throttle control?
Is the resistance less than 1
&?
Is the resistance less than 1
&?
Is the voltage less than 10 V?
"
):
Is the resistance more than 1
M&?
EN(H4SO 2.0)(diag)-104
Yes
Go to step 2. 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 poor
contact in ECM
connector.
Replace the ECM
if defective. <Ref.
to FU(H4SO 2.0)-
34, Engine Con-
trol Module
(ECM).>
Go to step 6. Repair the battery
short circuit in har-
ness between
ECM connector
and electronic
throttle control
connector.
Repair the poor Repair the short
contact in harness. circuit to sensor
Repair the elec- power supply.
tronic throttle con-
trol.
No