Yamaha WR450F 2021, Owner'S Service Manual, Page: 346 / 402

FUEL INJECTION SYSTEM
8-47
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).
Improperly connected

Con-
nect the coupler securely, or
repair/replace the wire harness.
Push 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.
3 Wire harness continuity. Open or short circuit

Replace
the wire harness.
Between battery terminal and
main relay.
red–red
red–red/white
Between main relay coupler and
ECU coupler.
brown–brown
blue/red–blue/red
Push 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.
4 Defective main relay. No operating sound

Replace
the main relay.
Or execute the diagnostic mode.
(Code No. 09)
Fuel system voltage is below 3
V

Replace the main relay.
Push 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.
5 Malfunction in ECU. Replace the ECU. Service is finished.
6 Delete the fault code. Confirm that the fault code has
a condition of “Recovered”
using the Yamaha diagnostic
tool, and then delete the fault
code.
Fault code No. 43
Item Fuel system voltage: incorrect voltage supplied to the main relay.