Yamaha WR250F Owner's Service Manual page 385

Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
1 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).
2 Wire harness continuity.
3 Defective AC magneto.
4 Malfunction in ECU.
46
Charging voltage is abnormal.
Able/Unable to start engine
Able/Unable to drive vehicle
—
—
—
Maintenance job
Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.
Open or short circuit Re-
place the wire harness.
Between rectifier/regulator
coupler and ECU coupler.
red–red
Between battery terminal and
ECU coupler.
red–red
Check the AC magneto.
Refer to "CHARGING SYS-
TEM" on page 9-12.
Defective AC magneto  Re-
place.
Replace the ECU.
9-51
FUEL INJECTION SYSTEM
Confirmation of service
completion
Start the engine and let it idle
for approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 2.
Start the engine and let it idle
for approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 3.
Start the engine and let it idle
for approximately 5 seconds.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 4.