Yamaha YZ 2020 Series, Owner'S Service Manual

Page: 326 / 376

FUEL INJECTION SYSTEM
8-39
Fault code No. 50
TIP
Before troubleshooting, disconnect the starter motor lead from the starter relay.
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).
Improperly connected

Con-
nect the coupler securely, or
repair/replace the wire harness.
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.
3 Wire harness continuity. 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
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.
4 Defective AC magneto. Check the AC magneto.
Refer to “CHECKING THE
GENERATOR” on page 5-39.
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.
5 Faulty 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. 50
Item ECU: faulty ECU memory.
Fail-safe system
Unable to start engine
Unable to drive vehicle
Diagnostic code No.
—
Diagnostic tool display
—
Procedure
—
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
Fault code No. 46
Item
Vehicle system power supply: normal voltage is not supplied to the
ECU.