Yamaha WR450FB 2012 Owner's Service Manual page 341

FUEL INJECTION SYSTEM
Fault code No.
21
Item
Coolant temperature sensor: open or short circuit detected.
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. d:06
Diagnostic tool display
Displays the coolant temperature.
Procedure
Compare the actually measured coolant temperature with the diag-
nostic tool display value.
Or- Probable cause of malfunc-
Maintenance job
Confirmation of service
der
tion and check
completion
1
Connection of coolant tern- Improperly connected
4
Set the main switch to "ON".
perature sensor coupler.
Connect the coupler securely Fault code number is not dis-
Check the locking condition
or repair/replace the wire har- played
4
Service is finished ..
of the coupler.
ness. Fault code number is dis-
Disconnect the coupler and pfayed
4
Go to next order.
check the pins (bent or bro-
ken terminals and locking
condition of the pins).
2
Connection of wire harness Improperly connected
4
Set the main switch to "ON".
ECU coupler. Connect the coupler securely Fault code number is not dis-
Check the locking condition or repair/replace the wire har- played
4
Service is finished.
of the coupler. ness. Fault code number is dis-
Disconnect the coupler and played
4
Go to next order.
check the pins (bent or bro-
ken terminals and locking
condition of the pins).
3 Wire harness continuity. Open or short circuit
4
Re- Set the main switch to "ON".
place the wire harness. Fault code number is not dis-
Between coolant temperature played
4
Service is finished.
sensor coupler and ECU cou- Fault code number is dis-
pier.
green/yellow-green/yellow
played
4
Go to next order.
black/blue-black/blue
4 Installed condition of coolant Improperly installed sensor Set the main switch to "ON".
temperature sensor.
4
Reinstall or replace the Fault code number is not dis-
Check for looseness or
sensor.
played
4
Service is finished.
pinching. Fault code number is dis-
played
4
Go to next order.
5 Defective coolant tempera-
Execute the diagnostic mode. Set the main switch to "ON".
ture sensor. (Code No. d:06)
Fault code number is not dis-
Replace if defective.
played
4
Service is finished.
Fault code number is dis-
played
4
Go to next order.
6
Malfunction in ECU. Replace the ECU.
TIP~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Make sure that the engine is completely cool before checking the intake air temperature sensor.
9-40