Subaru Legacy (2005 year). Service manual — part 354

EN(H4DOTC)(diag)-185

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

Step

Check

Yes

No

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:

Is the resistance less than 1
Ω?

Go to step 2.

Replace the elec-
tronic throttle con-
trol relay.

2

CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B362) No. 8 (+) — Chassis ground (

−

):

(B362) No. 5 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Go to step 3.

Repair the open or
ground short cir-
cuit of power sup-
ply circuit.

3

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Turn the ignition switch to ON.
4) Measure the voltage between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B362) No. 6 (+) — Chassis ground (

−

):

Is the voltage more than 10 V? Repair the power

supply short cir-
cuit of harness
between ECM and
electronic throttle
control.

Go to step 4.

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. 7 — Chassis ground:

Is the resistance more than 1
M

Ω?

Go to step 5.

Repair the ground
short circuit of har-
ness between
ECM and elec-
tronic throttle con-
trol relay.

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. 7:

Is the resistance less than 1
Ω?

Go to step 6.

Repair the open
circuit of harness
between ECM and
electronic throttle
control relay.

6

CHECK SENSOR OUTPUT.
1) Connect all the connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector terminals.

Connector & terminal

(B136) No. 18 (+) — (B136) No. 35 (

−

):

Is the voltage more than 0.4 V? Go to step 7.

Go to step 9.

EN(H4DOTC)(diag)-186

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

7

CHECK SENSOR OUTPUT.
1) Connect all the connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector terminals.

Connector & terminal

(B136) No. 29 (+) — (B136) No. 35 (

−

):

Is the voltage more than 0.8 V? Go to step 8.

Go to step 9.

8

CHECK POOR CONTACT.
Check poor contact in connector between
ECM and electronic throttle control.

Is there poor contact?

Repair the poor
contact.

Go to step 13.

9

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

(B136) No. 16 — (E57) No. 5:

Is the resistance less than 1
Ω?

Go to step 10.

Repair the open
circuit of harness
connector.

10

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
Measure the resistance between ECM connec-
tor and chassis ground.

Connector & terminal

(B136) No. 16 — Chassis ground:
(B136) No. 18 — Chassis ground:
(B136) No. 29 — Chassis ground:

Is the resistance more than 1
M

Ω?

Go to step 11.

Repair the ground
short circuit of har-
ness.

11

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

(E57) No. 5 (+) — Engine ground (

−

):

Is the voltage 4.5 — 5.5 V?

Go to step 12.

Repair the poor
contact in ECM
connector.
Replace the ECM
if defective. <Ref.
to FU(H4DOTC)-
34, Engine Con-
trol Module
(ECM).>

12

CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 — Engine ground:
(E57) No. 4 — Engine ground:

Is the resistance more than 10
Ω?

Go to step 13.

Repair the poor
contact in ECM
connector.
Replace the ECM
if defective. <Ref.
to FU(H4DOTC)-
34, Engine Con-
trol Module
(ECM).>

13

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.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>

Is the voltage 4.63 V?

Go to step 14.

Go to step 16.

Step

Check

Yes

No

EN(H4DOTC)(diag)-187

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

14

CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal
using Subaru Select Monitor.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>

Is the voltage 4.73 V?

Go to step 15.

Go to step 16.

15

CHECK POOR CONTACT.
Check poor contact in connector between
ECM and electronic throttle control.

Is there poor contact?

Repair the poor
contact.

Go to step 20.

16

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

(B136) No. 35 — (E57) No. 3:
(B136) No. 18 — (E57) No. 6:
(B136) No. 29 — (E57) No. 4:

Is the resistance less than 1
Ω?

Go to step 17.

Repair the open
circuit of harness
connector.

17

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

(E57) No. 3 — Engine ground:

Is the resistance less than 5
Ω?

Go to step 18.

Repair the poor
contact in ECM
connector.
Replace the ECM
if defective. <Ref.
to FU(H4DOTC)-
34, Engine Con-
trol Module
(ECM).>

18

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
Measure the voltage between electronic throt-
tle control connector and engine ground.

Connector & terminal

(E57) No. 6 (+) — Engine ground (

−

):

(E57) No. 4 (+) — Engine ground (

−

):

Is the voltage less than 10 V?

Go to step 19.

Repair the short
circuit of harness
between ECM
connector and
electronic throttle
control connector.

19

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Remove the ECM.
3) Measure the resistance between ECM con-
nectors.

Connector & terminal

(B136) No. 18 — (B136) No. 35:
(B136) No. 29 — (B136) No. 35:

Is the resistance more than 1
M

Ω?

Go to step 20.

Repair the short
circuit to sensor
power supply.

Step

Check

Yes

No

EN(H4DOTC)(diag)-188

ENGINE (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

20

CHECK SENSOR OUTPUT.
1) Turn the ignition switch to OFF.
2) Connect the connectors except for electric
throttle control relay.
3) Turn the ignition switch to ON.
4) Read the data of main throttle sensor signal
using Subaru Select Monitor.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>

Is the voltage 0.81 — 0.87 V?

Go to step 21.

Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.

21

CHECK SENSOR OUTPUT.
Read the data of sub throttle sensor signal
using Subaru Select Monitor.

NOTE:

• Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>

Is the voltage 1.64 — 1.70 V?

Go to step 22.

Repair the poor
contact in ECM
connector.
Replace the elec-
tronic throttle con-
trol if defective.

22

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
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. 5 — (E57) No. 2:
(B137) No. 4 — (E57) No. 1:

Is the resistance less than 1
Ω?

Go to step 23.

Repair the open
circuit of harness
connector.

23

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 (

−

):

Is the voltage less than 5 V?

Go to step 24.

Repair the power
supply short cir-
cuit of harness
between ECM and
electronic throttle
control.

24

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:

Is the resistance more than 1
M

Ω?

Go to step 25.

Repair the short
circuit of harness.

25

CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic
throttle control connector terminals.

Connector & terminal

(E57) No. 2 — (E57) No. 1:

Is the resistance more than 1
M

Ω?

Go to step 26.

Repair the short
circuit of harness.

Step

Check

Yes

No