Subaru Impreza 2003 Service Manual page 1356

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1)Start the engine.
2)Measure the ignition timing advance using
Subaru Select Monitor or OBD-II general scan
tool, while running the vehicle at approx. 30
km/h (19 MPH).
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4DOTC)-32, Subaru Select Mon-
itor.>
•OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR AND ECM CON-
NECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from AVCS cam-
shaft position sensor and ECM.
3)Measure the resistance of harness between
AVCS camshaft position sensor connector and
engine ground.
Connector & terminal
(E36) No. 1 — (B84) No. 2:
(E36) No. 2 — (B84) No. 3:
3 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR AND ECM CON-
NECTOR.
Measure the resistance of harness between
AVCS camshaft position sensor connector and
engine ground.
Connector & terminal
(E36) No. 1 — Engine ground:
(E36) No. 2 — Engine ground:
4 CHECK CONDITION OF AVCS CAMSHAFT
POSITION SENSOR.
5 CHECK AVCS CAMSHAFT POSITION SEN-
SOR.
1)Remove the AVCS camshaft position sen-
sor.
2)Measure the resistance between connector
terminals of AVCS camshaft position sensor.
Terminals
No. 1 — No. 2:
Check
Does the ignition timing
advance smoothly change,
according to engine output
change?
Idling: −2 — +2°
Vehicle running: −2 — +50°
Is the resistance less than 1
Ω?
Is the resistance more than 1M
Ω?
Is the AVCS camshaft position
sensor installation bolt tight-
ened securely?
Is the resistance 1 — 4 kΩ?
EN(H4DOTC)-180
Yes
Repair the poor Go to step 2.
contact in connec-
tor.
NOTE:
In this case, repair
the following:
• Poor contact in
AVCS camshaft
position sensor
• Poor contact in
ECM connector
Go to step 3. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
AVCS camshaft
position sensor
and ECM connec-
tor
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Go to step 4. Repair the ground
short circuit in har-
ness between
AVCS camshaft
position sensor
and ECM connec-
tor.
NOTE:
The harness be-
tween both con-
nectors
shielded.
the ground short
circuit in harness
together
shield.
Go to step 5. Tighten the AVCS
camshaft position
sensor installation
bolt securely.
Check oil pres- Replace the AVCS
sure passage and camshaft position
stuck of variable sensor. <Ref. to
valve timing sole- FU(H4DOTC)-31,
noid valve. AVCS Camshaft
Position Sensor.>
No
are
Repair
with