Subaru LEGACY 2003 Service Manual page 94

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
1 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1) Disconnect connector from pressure sen-
sor.
2) Turn ignition switch to ON.
3) Measure voltage between pressure sensor
connector and engine ground.
Connector & terminal
(E20) No. 3 (+) — Engine ground (–):
Is the measured value within the specified
value?
2 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1) Disconnect connector from ECM.
2) Measure resistance of harness between
ECM and pressure sensor connector.
Connector & terminal
(B136) No. 16 — (E20) No. 1:
(B136) No. 5 — (E20) No. 4:
Is the measured value less than the speci-
fied value?
3 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
Measure resistance of harness between ECM
connector and chassis ground.
Connector & terminal
(B136) No. 5 — Chassis ground:
(B136) No. 16 — Chassis ground:
Does the measured value exceed the specified
value?
4 CHECK INPUT SIGNAL FOR ECM.
1) Turn ignition switch to OFF.
2) Connect connector to ECM and pressure
sensor.
3) Turn ignition switch to ON.
4) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 5 (+) — Chassis ground (–):
Is the measured value within the specified
value?
5 CHECK INPUT SIGNAL FOR ECM.
1) Start engine, and idle it.
2) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 5 (+) — Chassis ground (–):
Is the measured value within the specified
value?
6 CHECK POOR CONTACT.
Check poor contact in pressure sensor con-
nector.
Is there poor contact in pressure sensor con-
nector?
Step
EN(H4SOw/oOBD)-92
Value
4.5 — 5.5 V
1 Ω
1 MΩ
2.3 — 2.5 V
1.2 — 1.8 V
There is poor contact.
Yes
Go to step 2. Repair open or
ground short cir-
cuit in harness
between ECM and
pressure sensor.
Go to step 3. Repair open circuit
in harness
between ECM and
pressure sensor
connector.
Go to step 4. Repair ground
short circuit in har-
ness between
ECM and pressure
sensor connector.
Go to step 5. Replace pressure
sensor. <Ref. to
FU(H4SOw/
oOBD)-32, Intake
Air Temperature
and Pressure Sen-
sor.>
Go to step 6. Replace pressure
sensor. <Ref. to
FU(H4SOw/
oOBD)-32, Intake
Air Temperature
and Pressure Sen-
sor.>
Repair poor con- Replace pressure
tact in pressure sensor. <Ref. to
sensor connector. FU(H4SOw/
oOBD)-32, Intake
Air Temperature
and Pressure Sen-
sor.>
No