Subaru Legacy 2004 Service Manual page 650

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 SENSOR OUTPUT.
Read the data of sub throttle sensor signal
using Subaru Select Monitor.
3 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and electronic throttle control.
4 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 & terminals
(B137) No. 23 — (E78) No. 5:
(B137) No. 24 — (E78) No. 2:
(B136) No. 17 — (E78) No. 4:
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 23 — Chassis ground:
(B137) No. 24 — Chassis ground:
(B136) No. 17 — Chassis ground:
6 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
(E78) No. 4 (+) — Engine ground (
7 CHECK SHORT CIRCUIT IN ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E78) No. 5 — Engine ground:
(E78) No. 2 — Engine ground:
8 CHECK SENSOR OUTPUT.
1) Connect all the connectors.
2) Turn the ignition switch to ON.
3) Read the data of main throttle sensor signal
using Subaru Select Monitor.
9 CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal
using Subaru Select Monitor.
Check
Is the voltage more than 0.4 V? Go to step 2.
Is the voltage more than 0.8 V? Go to step 3.
Is there poor contact?
Is the resistance less than 1
&?
Is the resistance more than 1
M&?
Is the voltage 4.5 — 5.5 V?
"
):
Is the resistance more than 10
&?
Is the voltage less than 4.63
V?
Is the voltage less than 4.73
V?
EN(H4SO 2.0)(diag)-218
Yes
Go to step 4.
Go to step 4.
Repair the poor Go to step 14.
contact.
Go to step 5. Repair the open
circuit of harness
connector.
Go to step 6. Repair the ground
short circuit of har-
ness.
Go to step 7. 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 8. 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 9. Go to step 11.
Go to step 10. Go to step 11.
No