Yamaha YZ 2020 Series Owner's Service Manual page 326

Fault code No.
Item
2 Connection of AC magneto cou-
pler.
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 AC magneto.
5 Faulty ECU.
6 Delete the fault code.
Fault code No. 50
TIP
Before troubleshooting, disconnect the starter motor lead from the starter relay.
Fault code No.
Item
Fail-safe system
Diagnostic code No.
Diagnostic tool display
Procedure
Probable cause of malfunc-
Item
tion and check
46
Vehicle system power supply: normal voltage is not supplied to the
ECU.
Improperly connected  Con-
nect the coupler securely, or
repair/replace the wire harness.
Open or short circuit  Replace
the wire harness.
Between rectifier/regulator cou-
pler and battery terminal.
red–red
black–black
Between rectifier/regulator cou-
pler and AC magneto coupler.
white–white
Check the AC magneto.
Refer to "CHECKING THE
GENERATOR" on page 5-39.
Replace the ECU.
Confirm that the fault code has
a condition of "Recovered"
using the Yamaha diagnostic
tool, and then delete the fault
code.
50
ECU: faulty ECU memory.
Unable to start engine
Unable to drive vehicle
—
—
—
Maintenance job
8-39
FUEL INJECTION SYSTEM
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.
Confirmation of service com-
pletion