Subaru Legacy 2004 Service Manual page 957

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of tumble generator valve
position sensor signal using Subaru Select
Monitor or OBD-II general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.5)(diag)-26, Subaru Select
Monitor.>
• OBD-II general scan tool
For detailed operation procedures, refer to the
operation manual of OBD-II general scan tool.
2 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground while throttle valve is fully
closed.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
3 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
4 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 27 (+) — Chassis ground (
5 CHECK INPUT SIGNAL FOR ECM. (USING
SUBARU SELECT MONITOR)
Measure the voltage between ECM connector
and chassis ground.
Check
Is the voltage less than 0.1 V? Go to step 2.
Is the voltage more than 4.5 V? Go to step 4.
"
):
Shake the ECM harness and
connector, while monitoring
value of voltage meter. Does
the voltage change?
"
):
Is the voltage less than 0.1 V? Go to step 6.
"
):
Shake the ECM harness and
connector, while monitoring
value of Subaru Select Moni-
tor. Does the voltage change?
EN(H4SO 2.5)(diag)-198
Yes
Even if malfunction
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector may be the
cause.
NOTE:
In this case, repair
the following:
• Poor contact in
tumble generator
valve position sen-
sor connector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Go to step 3.
Repair the poor Contact your Sub-
contact in ECM aru distributor ser-
connector. vice.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Go to step 5.
Repair the poor Go to step 6.
contact in ECM
connector.
No
be-
probable
multiple