Subaru Impreza 2004 Service Manual page 31

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
3 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 8 (+) — Chassis ground ( − − − − ):
4 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from manifold
absolute pressure sensor.
3)Turn the ignition switch to ON.
4)Measure the voltage between manifold abso-
lute pressure sensor connector and engine
ground.
Connector & terminal
(E21) No. 3 (+) — Engine ground ( − − − − ):
5 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ECM.
3)Measure the resistance of harness between
ECM and manifold absolute pressure sensor
connector.
Connector & terminal
(B135) No. 8 — (E21) No. 1:
6 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
Measure the resistance of harness between
ECM and manifold absolute pressure sensor
connector.
Connector & terminal
(B135) No. 19 — (E21) No. 2:
7 CHECK POOR CONTACT.
Check poor contact in manifold absolute pres-
sure sensor connector.
Check
Is the voltage more than 4.5 V? Go to step 4.
Is the voltage more than 4.5 V? Go to step 5.
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in mani-
fold absolute pressure sensor
connector?
EN(H4DOTC)(diag)-110
Yes
Contact your Sub-
aru distributor ser-
vice.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
Go to step 6. Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
Go to step 7. Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
Repair the poor Replace the mani-
contact in mani- fold absolute pres-
fold absolute pres- sure sensor. <Ref.
sure sensor to FU(H4DOTC)-
connector. 35, Manifold Abso-
lute Pressure Sen-
sor.>
No
be-
probable
multiple