Yamaha YZ450F Owner's Service Manual page 217

Fault code No.
Symptom
Fail-safe system
Diagnostic code No.
FI diagnostic tool display
Checking method
Item Item/components and probable cause
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)
2 Continuity of harness
3 Malfunction of the rectifier/regulator.
46
Power supply to the ECU is not normal.
Able to start (depending on circumstances)
Able to drive vehicle (depending on circumstances)
—
—
—
FUEL INJECTION SYSTEM
Check or maintenance job
Poor connection → Properly con-
nect, repair, or replace.
Open or short circuit → Replace.
Between Rectifier/regulator and
the ECU
(Red–Red/White)
Between Rectifier/regulator and
the condenser.
(Red–Red)
Defective → Replace.
Refer to "CHECKING THE RECTI-
FIER/REGULATOR" section.
7-31
Checking method
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.
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.
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.