2016 YAMAHA YZ450F ECU

TROUBLESHOOTING
9-2
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
EASB111352POOR MEDIUM-AND-HIGH-SPEED PER-
FORMANCE
Refer to “STARTING FAILURES” on page 9-1.
Engine
1. Air filter
• Clogged air filter element
Fuel system
1. Fuel pump
• Faulty fuel pump
2. Throttle body
• Defective throttle body
3. ECU
• Faulty ECU
EASB111353SHIFTING IS DIFFICULT
Refer to “CLUTCH” on page 5-38.
EASB111354SHIFT PEDAL DOES NOT MOVE
Engine
1. Shift shaft
• Bent shift shaft
2. Shift drum and shift forks
• Foreign object in a shift drum groove
• Seized shift fork
• Bent shift fork guide bar
3. Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
EASB111355JUMPS OUT OF GEAR
Engine
1. Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
2. Shift forks
• Worn shift fork
3. Shift drum
• Incorrect axial play
• Worn shift drum groove
4. Transmission
• Worn gear dog
EASB111356
CLUTCH SLIPS
Engine
1. Clutch
• Improperly assembled clutch
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
EASB111357CLUTCH DRAGS
Engine
1. Clutch
• Unevenly tensioned clutch springs
• Warped pressure plate
• Bent clutch plate
• Swollen friction plate
• Bent clutch push rod
• Damaged clutch boss
• Burnt primary driven gear bushing
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (high)
• Deteriorated oil
EASB111358OVERHEATING
Engine
1. Cylinder head and piston
• Heavy carbon buildup
• Clogged coolant passages
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity
• Inferior oil quality
Cooling system
1. Coolant
• Low coolant level
2. Radiator
• Damaged or leaking radiator
• Faulty radiator cap
• Bent or damaged radiator fin
3. Water pump
• Damaged or faulty water pump
• Damaged hose
• Improperly connected hose
• Damaged pipe
• Improperly connected pipe

TROUBLESHOOTING
9-3
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
2. Air filter
• Clogged air filter element
Chassis
1. Brake(s)
• Dragging brake
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
2. Ignition system
• Faulty ECU
• Faulty coolant temperature sensor
EASB111359OVERCOOLING
Cooling system
1. Coolant temperature sensor
• Faulty coolant temperature sensor
EASB111360POOR BRAKING PERFORMANCE
Chassis
1. Brake(s)
• Worn brake pad
• Worn brake disc
• Air in hydraulic brake system
• Leaking brake fluid
• Defective master cylinder kit
• Faulty brake caliper kit
• Faulty brake caliper seal
• Loose union bolt
• Damaged brake hose
• Oil or grease on the brake disc
• Oil or grease on the brake pad
• Incorrect brake fluid level
EASB111361FRONT FORK OIL LEAKING
Chassis
1. Front fork
• Bent, damaged, or rusty inner tube
• Cracked or damaged outer tube
• Improperly installed oil seal
• Damaged oil seal lip
• Incorrect oil level (high)
• Loose damper rod assembly bolt
• Damaged damper rod assembly bolt copper
washer
• Cracked or damaged cap bolt O-ring
EASB111362FAULTY FRONT FORK LEGS
Chassis
1. Front fork
• Bent or damaged inner tube
• Bent or damaged outer tube
• Broken fork spring
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EASB111363UNSTABLE HANDLING
Chassis
1. Handlebar
• Bent or improperly installed handlebar
2. Steering head components
• Improperly installed upper bracket
• Improperly installed lower bracket
(improperly tightened ring nut)
• Bent steering stem
• Damaged ball bearing or bearing race
3. Front fork leg (s)
• Uneven oil levels (both front fork legs)
• Unevenly tensioned fork spring (both front
fork legs)
• Broken fork spring
• Bent or damaged inner tube
• Bent or damaged outer tube
4. Swingarm
• Worn bearing or bushing
• Bent or damaged swingarm
5. Rear shock absorber assembly (-ies)
• Faulty rear shock absorber spring
• Leaking oil or gas
6. Tire (s)
• Uneven tire pressures (front and rear)
• Incorrect tire pressure
• Uneven tire wear
7. Wheel (s)
• Incorrect wheel balance
• Broken or loose spoke
• Damaged wheel bearing
• Bent or loose wheel axle
• Excessive wheel runout
8. Frame
• Bent frame
• Damaged steering head pipe
• Improperly installed bearing race

LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
9-4
EASB111364
LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
LIST OF DIAGNOSTIC CODES
COMMUNICATION ERROR WITH YAMAHA DIAGNOSTIC TOOLFault
codeITEM Page
12 Crankshaft position sensor: no normal signals are received from the
crankshaft position sensor.8-14
13 Intake air pressure sensor: open or short circuit detected. 8-15
14 Intake air pressure sensor: hose system malfunction (clogged or de-
tached hose)8-16
15 Throttle position sensor: open or short circuit detected. 8-17
16 Throttle position sensor: stuck throttle position sensor is detected. 8-19
21 Coolant temperature sensor: open or short circuit detected. 8-20
22 Intake air temperature sensor: open or short circuit detected. 8-21
30 The vehicle has overturned. 8-22
33 Ignition coil: open or short circuit detected in the primary lead of the
ignition coil.8-23
39 Injector: open or short circuit detected. 8-24
41 ECU: built-in lean angle sensor malfunction 8-25
44 EEPROM fault code No.: an error is detected while reading or writing
on EEPROM.8-26
46 Vehicle system power supply: normal voltage is not supplied to the
ECU.8-27
50 ECU: faulty ECU memory 8-28
Fault
codeITEM Page
Waiting
for con-
nectionNo communication signal is received from the ECU.
8-28
Er-2 Signals from the ECU cannot be received within the specified period
of time.8-29
Er-3 Data from the ECU cannot be received correctly. 8-30
Er-4 Registered data cannot be received from the Yamaha diagnostic tool. 8-31

LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
9-5
SENSOR OPERATION TABLE
Diag-
nostic
code
No.ITEM Display Procedure
01 Throttle angle
• Fully closed position
• Fully opened positionDisplays the throttle angle.
• 11–14
• 109–116• Check with throttle fully
closed.
• Check with throttle fully
opened.
03 Pressure of suction pipe Displays the intake air pres-
sure.The atmospheric pressure
is displayed on the Yamaha
diagnostic tool.
05 Intake air temperature Displays the intake air tem-
perature.Compare the actually mea-
sured intake air tempera-
ture with the Yamaha
diagnostic tool display val-
ue.
06 Coolant temperature Displays the coolant temper-
ature.Compare the actually mea-
sured coolant temperature
with the Yamaha diagnostic
tool display value.
08 Lean angle sensor
• Upright
•OverturnDisplays the output voltage.
• 1.0 (V)
• 4.0 (V)Remove the ECU, and in-
cline it 45 ° or more.
09 Monitor voltage Displays the voltage of the
external battery connected to
the Yamaha diagnostic tool.
• Approximately 12.0 (V)—
21 Neutral switch
• Gear in neutral
• Gear not in neutral•ON
•OFFOperate the shift pedal.
25 Gear position switch
• Gear in 1st or 2nd
• Gear not in 1st or 2nd•ON
•OFFOperate the shift pedal.
60 EEPROM fault code No.
display
• No fault
• CO adjustment valve
• Power Tuner injection cor-
rection setting 0–8, or
Power Tuner ignition tim-
ing correction setting 0–8•00
•01
•07—
61 Malfunction history ( )
code No. display *1
• There is no history.
• There is some history.•00
• Other: Displays the fault
code of ( ).—

EASB111381
WIRING DIAGRAM
YZ450F/YZ450FG 2016
1. Crankshaft position sensor
2. AC magneto
3. Rectifier/regulator
4. Joint connector
5. Condenser
6. Coupler for connecting option-
al part
7. Engine stop switch
8. Neutral switch
9. Launch control switch
10. ECU
11. Ignition coil
12. Spark plug
13. Fuel injector
14. Fuel pump
15. Intake air temperature sensor
16. Coolant temperature sensor
17. Throttle position sensor
18. Intake air pressure sensor
19. Ignition coil sub-lead
EASB111382COLOR CODE
BBlack
Gy Gray
LBlue
Lg Light green
O Orange
PPink
RRed
Sb Sky blue
Y Yellow
B/L Black/Blue
B/R Black/Red
B/W Black/White
B/Y Black/Yellow
Br/W Brown/White
G/W Green/White
L/W Blue/White
P/B Pink/Black
R/B Red/Black
Y/G Yellow/Green
Y/R Yellow/Red
Y/W Yellow/White