Yamaha MBK MW125 2014, Service Manual

Page: 335 / 380

FUEL INJECTION SYSTEM
8-38
TIP
If fault code numbers “21” and “37” are both indicated, take the actions specified for fault code number
“21” first.
Fault code No. 22
3 Wire harness continuity. Open or short circuit
→
Replace
the wire harness.
Between coolant temperature
sensor coupler and ECU cou-
pler.
green/red–green/red
black/blue–black/blue
Turn the main switch to “ON”.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item 4.
4 Installed condition of coolant
temperature sensor.
Check for looseness or pinch-
ing. Improperly installed sensor
→
Reinstall or replace the sensor.
Turn the main switch to “ON”.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item 5.
5 Defective coolant temperature
sensor. Execute the diagnostic mode.
(Code No. 06)
When engine is cold:
Displayed temperature is close
to the ambient temperature.
The displayed temperature is
not close to the ambient tem-
perature
→
Check the coolant
temperature sensor.
Replace thermostat assembly, if
defective.
Refer to “CHECKING THE
COOLANT TEMPERATURE
SENSOR” on page 8-67.
Turn the main switch to “ON”.
Fault code number is not dis-
played
→
Service is finished.
Fault code number is displayed
→
Go to item 6.
6 Malfunction in ECU. Replace the ECU.
Refer to “REPLACING THE
ECU (engine control unit)” on
page 8-59.
Fault code No. 21
Item Coolant temperature sensor: open or short circuit detected.
Fault code No. 22
Item Intake air temperature sensor: open or short circuit detected.
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. 05
Tool display Displays the intake air temperature.
Procedure
Compare the actually measured intake air temperature with the meter
display value.
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion