Yamaha WR250F Owner's Service Manual page 389

TIP
Before troubleshooting, disconnect the starter motor lead from the starter relay.
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 Yamaha diag-
nostic tool 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 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).
3 Wire harness continuity.
4 Yamaha diagnostic tool mal-
function.
5 Malfunction in ECU.
Er-4
Registered data cannot be received from the Yamaha diagnos-
tic tool.
Able to start engine
Able to drive vehicle
—
—
—
Maintenance job
Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.
Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.
Open or short circuit  Re-
place the wire harness.
light green–light green
Replace the Yamaha diag-
nostic tool.
Replace the ECU.
9-55
FUEL INJECTION SYSTEM
Confirmation of service
completion
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 2.
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 3.
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 4.
Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 5.