Subaru 2004 LEGACY Service Manual page 173

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to electronic throttle
control relay terminals No. 5 and No. 6.
4) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 7 — No. 8:
2 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throt-
tle control relay connector and chassis ground.
Connector & terminal
(B362) No. 7 (+) — Chassis ground (
(B362) No. 5 (+) — Chassis ground (
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B362) No. 6 (+) — Chassis ground (
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B362) No. 6 — Chassis ground:
(B362) No. 8 — Chassis ground:
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.
Connector & terminal
(B135) No. 35 — (B362) No. 6:
(B137) No. 6 — (B362) No. 8:
6 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.
7 CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal
using Subaru Select Monitor.
8 CHECK POOR CONTACT.
Check the poor contact in connector between
ECM and electronic throttle control.
Check
Is the resistance less than 1
Ω?
Is the voltage more than 5 V?
−
):
−
):
Is the voltage less than 5 V?
−
):
Is the resistance more than 1
MΩ?
Is the resistance less than 1
Ω?
Is the voltage more than 0.4 V? Go to step 7.
Is the voltage more than 0.8 V? Go to step 8.
Is there poor contact?
EN(H6DO)(diag)-242
Yes
Go to step 2. Replace the elec-
tronic throttle con-
trol relay.
Go to step 3. Repair the open or
ground short cir-
cuit of power sup-
ply circuit.
Go to step 4. Repair power sup-
ply short circuit in
harness between
ECM and elec-
tronic throttle con-
trol.
Go to step 5. Repair the ground
short circuit in har-
ness between
ECM and elec-
tronic throttle con-
trol relay.
Go to step 6. Repair the open
circuit in harness
between ECM and
electronic throttle
control relay.
Go to step 9.
Go to step 9.
Repair the poor Go to step 13.
contact.
No