Yamaha YZ450FX 2019 Owner's Service Manual page 337

Fault code No.
Item
2 Connection of wire harness
ECU coupler.
Check the locking condition of
the coupler.
Disconnect the coupler and
check the pins (bent or broken
terminals and locking condition
of the pins).
3 Wire harness continuity.
4 Defective main relay.
5 Malfunction in ECU.
6 Delete the fault code.
43
Fuel system voltage: incorrect voltage supplied to the main relay
and CCU.
Improperly connected  Con-
nect the coupler securely or
repair/replace the wire harness.
Open or short circuit  Replace
the wire harness.
Between battery terminal and
ECU coupler.
red–red
red–red/white
Between main relay coupler and
ECU coupler.
brown–brown
blue/red–blue/red
No operating sound  Replace
the main relay.
Execute the diagnostic mode.
(Code No. 09)
Fuel system voltage is below 3
V  Replace the main relay.
Replace the ECU.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
8-42
FUEL INJECTION SYSTEM
Press the start switch and the
engine stop switch alternately to
switch the power supply (= main
relay) from "ON  OFF  ON".
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 6 and finish the service.
Condition is "Detected"  Go to
item 3.
Press the start switch and the
engine stop switch alternately to
switch the power supply (= main
relay) from "ON  OFF  ON".
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 6 and finish the service.
Condition is "Detected"  Go to
item 4.
Press the start switch and the
engine stop switch alternately to
switch the power supply (= main
relay) from "ON  OFF  ON".
Check the condition of the fault
code using the malfunction
mode of the Yamaha diagnostic
tool.
Condition is "Recovered"  Go
to item 6 and finish the service.
Condition is "Detected"  Go to
item 5.
Service is finished.