Yamaha YZ450FP 2023, Owner'S Service Manual

Page: 318 / 388

FUEL INJECTION SYSTEM
8-19
EAM30286
TROUBLESHOOTING DETAILS (FAULT CODE)
This section describes the measures per fault code number displayed on the Yamaha diagnostic tool.
Check and service the items or components that are the probable cause of the malfunction following
the order given.
After the check and service of the malfunctioning part have been completed, delete the fault codes dis-
played on the Yamaha diagnostic tool according to the reinstatement method.
Fault code No.:
Fault code number displayed on the Yamaha diagnostic tool when the engine failed to work normally.
Diagnostic code No.:
Diagnostic code number to be used when the diagnostic mode is operated. Refer to “DIAGNOSTIC
CODE: SENSOR OPERATION TABLE” on page 9-12.
Parts connected to the ECU
The following parts are connected to the ECU.
When checking for a power short circuit, the couplers must be disconnected from all of the following
parts beforehand.
Fault code No. 8
• Crankshaft position sensor • Intake air pressure sensor
• Fuel injector • Coolant temperature sensor
• Ignition coil • Intake air temperature sensor
• Throttle position sensor
Fault code No. 8
Item Gear position switch: open or short circuit detected.
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. 25
Diagnostic tool display
Displays the gear position.
• N (gear in neutral)
• 1 (gear in 1st or 2nd )
• 3 (gear in other than 1st or 2nd)
Procedure —
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
1 Connection of gear position
switch 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).
Improperly connected

Con-
nect the coupler securely, or
repair/replace the wire harness.
Start switch to ON (no need to
start the engine), change the
gear position from neutral posi-
tion to 1st

2nd

…

5th
position. (When doing so, be
sure to hold each position for 10
seconds or more.)
And then check the condition of
the fault code using the mal-
function mode of the Yamaha
diagnostic tool.
Condition is “Recovered”

Go
to item 7 and finish the service.
Condition is “Detected”

Go to
item 2.