Yamaha YZ450FP 2023, Owner'S Service Manual

Page: 319 / 388

FUEL INJECTION SYSTEM
8-20
2 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).
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 3.
3 Wire harness continuity. Open or short circuit

Replace
the wire harness.
Between gear position switch
coupler and ECU coupler.
pink–pink
white/blue–white/blue
yellow/green–yellow/green
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 4.
4 Mounted condition of gear posi-
tion switch.
Check for looseness or pinch-
ing.
Improperly mounted switch

Remount or replace the switch.
Refer to “ENGINE REMOVAL”
on page 5-2.
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 5.
5 Defective gear position switch. Execute the diagnostic mode.
(Code No. 25)
The values are indicated
according to the gear position.
Gear in neutral: N
Gear in 1st or 2nd: 1
Gear in other than 1st or 2nd: 3
Abnormal display

Gear posi-
tion switch is defective

Replace the gear position
switch.
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 6.
6 Faulty ECU. Replace the ECU. Service is finished.
Fault code No. 8
Item Gear position switch: open or short circuit detected.