Yamaha YZ450F(D), Owner'S Service Manual

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7-31
FUEL INJECTION SYSTEM
Fault code No. 46
Symptom Power supply to the ECU is not normal.
Fail-safe system Able to start (depending on circumstances)
Able to drive vehicle (depending on circumstances)
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins) Poor connection
→
Properly con-
nect, repair, or replace.
Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed
→
Service is
finished.
Fault code number is dis-
played
→ Refer to item 2.
2 Continuity of harness Open or short circuit
→
Replace.
Between Rectifier/regulator and
the ECU
(Red–Red/White)
Between Rectifier/regulator and
the condenser.
(Red–Red)
Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed
→
Service is
finished.
Fault code number is dis-
played
→ Refer to item 3.
3 Malfunction of the rectifier/regulator. Defective
→
Replace.
Refer to "CHECKING THE RECTI-
FIER/REGULATOR" section.
Start the engine, set the
switch on the FI diagnostic
tool sub-wire harness to
"OFF" while the engine is
idling, and let the engine
continue to idle for 5 sec-
onds or more.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed
→
Service is
finished.
Fault code number is dis-
played
→ Refer to item 4.