Yamaha YZ250FM 2021 Owner's Service Manual page 314

Fault code No. 39
TIP
Disconnect the fuel pump coupler when this diagnostic tool is used.
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Actuation
Procedure
Probable cause of malfunc-
Item
tion and check
1 Connection of injector coupler.
Check the locking condition of
the coupler.
Disconnect the coupler, and
check the pins (for bent or bro-
ken terminals and locking condi-
tion of the pins).
2 Defective injector.
3 Connection of wire harness
ECU coupler.
Check the locking condition of
the coupler.
Disconnect the coupler, and
check the pins (for bent or bro-
ken terminals and locking condi-
tion of the pins).
4 Wire harness continuity.
5 Faulty ECU.
39
Injector: open or short circuit detected.
Unable to start engine
Unable to drive vehicle
36
Actuates injector five times at one-second intervals.
"WARNING" on the Yamaha diagnostic tool blinks five times when the
injector is actuated.
Check that injector is actuated five times by listening for the operating
sound.
Maintenance job
Improperly connected  Con-
nect the coupler securely, or
repair/replace the wire harness.
Check the injector.
Refer to "CHECKING THE
INJECTOR" on page 8-51.
Improperly connected  Con-
nect the coupler securely, or
repair/replace the wire harness.
Open or short circuit  Replace
the wire harness.
Between injector coupler and
ECU coupler.
red/black–red/black
Between injector coupler and
starter relay.
red/blue–red/blue
red–red
red/yellow–red/yellow
Replace the ECU.
8-29
FUEL INJECTION SYSTEM
Confirmation of service com-
pletion
Start the engine and let it idle for
approximately 5 seconds.
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 2.
Start the engine and let it idle for
approximately 5 seconds.
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.
Start the engine and let it idle for
approximately 5 seconds.
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.
Start the engine and let it idle for
approximately 5 seconds.
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.