Subaru 2002 IMPREZA Service Manual page 935

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1)Disconnect the connector from pressure
sensor.
2)Turn the ignition switch to ON.
3)Measure the voltage between pressure sen-
sor connector and engine ground.
Connector & terminal
(E20) No. 3 (+) — Engine ground (–):
2 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1)Disconnect the connector from ECM.
2)Measure the 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 the 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 the ignition switch to OFF.
2)Connect the connector to ECM and pressure
sensor.
3)Turn the ignition switch to ON.
4)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 5 (+) — Chassis ground (–):
5 CHECK INPUT SIGNAL FOR ECM.
1)Start the engine, and idle it.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 5 (+) — Chassis ground (–):
6 CHECK POOR CONTACT.
Check poor contact in pressure sensor con-
nector.
Check
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 pres-
sure sensor connector?
EN(w/oOBD)-101
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the open or
ground short cir-
cuit in harness
between ECM and
pressure sensor.
Go to step 3. Repair the open
circuit in harness
between ECM and
pressure sensor
connector.
Go to step 4. Repair the ground
short circuit in har-
ness between
ECM and pressure
sensor connector.
Go to step 5. Replace the pres-
sure sensor. <Ref.
to FU(w/oOBD)-
38, Intake Air
Temperature and
Pressure Sensor.>
Go to step 6. Replace the pres-
sure sensor. <Ref.
to FU(w/oOBD)-
38, Intake Air
Temperature and
Pressure Sensor.>
Repair the poor Replace the pres-
contact in pres- sure sensor. <Ref.
sure sensor con- to FU(w/oOBD)-
nector. 38, Intake Air
Temperature and
Pressure Sensor.>
No