2014 YAMAHA YZ450F ECU

TROUBLE SHOOTING
9-2
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
EAS1SL1353POOR 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
EAS1SL1354FAULTY GEAR SHIFTING
Shifting is difficult
Refer to “CLUTCH” on page 5-37.
EAS1SL1355SHIFT PEDAL DOES NOT MOVE
Shift shaft
• Bent shift shaft
Shift drum and shift forks
• Foreign object in a shift drum groove
• Seized shift fork
• Bent shift fork guide bar
Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
EAS1SL1356JUMPS OUT OF GEAR
Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
Shift forks
• Worn shift fork
Shift drum
• Incorrect axial play
• Worn shift drum groove
Transmission
• Worn gear dog
EAS1SL1357FAULTY CLUTCH
Clutch slips
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
Clutch drags
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
EAS1SL1358OVERHEATING
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

TROUBLE SHOOTING
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
EAS1SL1359OVERCOOLING
Cooling system
• Faulty coolant temperature sensor
EAS1SL1360POOR BRAKING PERFORMANCE
• 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
EAS1SL1361FAULTY FRONT FORK LEGS
Leaking oil
• 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
Malfunction
• Bent or damaged inner tube
• Bent or damaged outer tube
• Broken fork spring
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EAS1SL1362UNSTABLE HANDLING
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
EAS1SL1363
LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
LIST OF DIAGNOSTIC CODES
COMMUNICATION ERROR WITH YAMAHA DIAGNOSTIC TOOL
Fault
codeITEMPage
12Crankshaft position sensor: no normal signals are received from the
crankshaft position sensor.8-14
13Intake air pressure sensor: open or short circuit detected.8-15
14Intake air pressure sensor: hose system malfunction (clogged or de-
tached hose)8-16
15Throttle position sensor: open or short circuit detected.8-17
16Throttle position sensor: stuck throttle position sensor is detected.8-19
21Coolant temperature sensor: open or short circuit detected.8-20
22Intake air temperature sensor: open or short circuit detected.8-21
30The vehicle has overturned.8-22
33Ignition coil: open or short circuit detected in the primary lead of the
ignition coil.8-23
39Injector: open or short circuit detected.8-25
41ECU: built-in lean angle sensor malfunction8-25
44EEPROM fault code No.: an error is detected while reading or writing
on EEPROM.8-26
46Vehicle system power supply: normal voltage is not supplied to the
ECU.8-27
50ECU: faulty ECU memory8-28
Fault
codeITEMPage
Waiting
for con
-
nection
No communication signal is received from the ECU.
8-28
Er-2Signals from the ECU cannot be received within the specified period
of time.8-29
Er-3Data from the ECU cannot be received correctly.8-30
Er-4Registered data cannot be received from the Yamaha diagnostic tool.8-31

LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
9-5
SENSOR OPERATION TABLEDiag-
nostic code No. ITEM Display Procedure
01 Throttle angle • Fully closed position
• Fully opened position Displays 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
•Overturn Displays 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
•OFF Operate the shift pedal.
25 Gear position sensor • Gear in 1st or 2nd
• Gear not in 1st or 2nd •ON
•OFF Operate 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 ( ). —

EAS1SL1380
WIRING DIAGRAM
YZ450F 2014
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. ECU
10. Ignition coil
11. Spark plug
12. Injector
13. Fuel pump
14. Intake air temperature sensor
15. Coolant temperature sensor
16. Throttle position sensor
17. Intake air puressure sensorEAS1SL1381COLOR CODE
BBlack
GyGray
LBlue
LgLight green
OOrange
PPink
RRed
SbSky blue
YYellow
B/LBlack/Blue
B/RBlack/Red
B/WBlack/White
B/YBlack/Yellow
Br/WBrown/White
G/WGreen/White
P/BPink/Black
R/BRed/Black