Subaru Legacy 2002 Service Manual page 914

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
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 (–):
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:
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:
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 (–):
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 (–):
6 CHECK POOR CONTACT.
Check poor contact in pressure sensor con-
nector.
Step
Is the voltage between 4.5
and 5.5 V?
Is the resistance less than
1 Ω?
Is the resistance more than
1 MΩ?
Is the voltage between 2.3
and 2.5 V?
Is the voltage between 1.2
and 1.8 V?
Is there poor contact in
pressure sensor connec-
tor?
EN(w/oOBD)-103
Check Yes
Go to step 2.
Go to step 3.
Go to step 4.
Go to step 5.
Go to step 6.
Repair poor con-
tact in pressure
sensor connector.
Engine (Diagnostics)
No
Repair open or
ground short cir-
cuit in harness
between ECM
and pressure sen-
sor.
Repair open cir-
cuit in harness
between ECM
and pressure sen-
sor connector.
Repair ground
short circuit in
harness between
ECM and pres-
sure sensor con-
nector.
Replace pressure
sensor. <Ref. to
FU(w/oOBD)-35,
Intake Air Tem-
perature and
Pressure Sensor.>
Replace pressure
sensor. <Ref. to
FU(w/oOBD)-35,
Intake Air Tem-
perature and
Pressure Sensor.>
Replace pressure
sensor. <Ref. to
FU(w/oOBD)-35,
Intake Air Tem-
perature and
Pressure Sensor.>