YAMAHA YZ450F 2016 Owners Manual

8
ELECTRICAL SYSTEM
IGNITION SYSTEM.......................................................................................... 8-2
CIRCUIT DIAGRAM ................................................................................... 8-2
TROUBLESHOOTING ............................................................................... 8-4
CHARGING SYSTEM....................................................................................... 8-6
CIRCUIT DIAGRAM ................................................................................... 8-6
TROUBLESHOOTING ............................................................................... 8-8
FUEL INJECTION SYSTEM........................................................................... 8-10
CIRCUIT DIAGRAM ................................................................................. 8-10
YAMAHA DIAGNOSTIC TOOL ................................................................ 8-12
TROUBLESHOOTING DETAILS ............................................................. 8-13
FUEL PUMP SYSTEM.................................................................................... 8-32
CIRCUIT DIAGRAM ................................................................................. 8-32
TROUBLESHOOTING ............................................................................. 8-34
ELECTRICAL COMPONENTS....................................................................... 8-36
CHECKING THE SWITCHES .................................................................. 8-38
CHECKING THE IGNITION SPARK GAP................................................ 8-41
CHECKING THE SPARK PLUG CAP ...................................................... 8-41
CHECKING THE IGNITION COIL ............................................................ 8-41
CHECKING THE CRANKSHAFT POSITION SENSOR........................... 8-42
CHECKING THE ECU .............................................................................. 8-42
CHECKING THE STATOR COIL ............................................................. 8-42
CHECKING THE RECTIFIER/REGULATOR ........................................... 8-43
CHECKING THE COOLANT TEMPERATURE SENSOR........................ 8-43
CHECKING THE THROTTLE POSITION SENSOR ................................ 8-44
CHECKING THE THROTTLE POSITION SENSOR INPUT VOLTAGE .. 8-45
CHECKING THE INTAKE AIR PRESSURE SENSOR ............................ 8-45
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ..................... 8-45
CHECKING THE NEUTRAL SWITCH ..................................................... 8-46
CHECKING THE FUEL INJECTOR ......................................................... 8-46

8-1
EASB111318
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.

IGNITION SYSTEM
8-2
EASB111319
IGNITION SYSTEM
EASB111320CIRCUIT DIAGRAM
ONOFF
ONOFF
B R
RRRRRRRR
BBBBBB
LLL
B/LB/LB/LB/LB/LB/L
B/L
Gy
W
W
W
W
R
R
B
B
B
B
RY/RY/G
Y/GY/B
Y/B
Y/W
Y/WB/YL/WB/R
B/Y
B/Y
B/W
R/B
R/B
B/R
B/R
G/WP/B
P/B
B/L
B/L
B/L
G/W
Br/W
Br/W
B/LB/L
B/W
Y/RSbP
Sb
Sb
P
P
P
L
L
LY
Y
B
B
LgGy
Lg
R
R
R
R
R
R
R
O
O
O
O
WWW W
W W
W W
R B
B/LGyB Gy
BRRB
RLgB/W
B/YB
B B
PP/LSbSbY/WP
B RY/R Y/GBB/WWR/Y
BGy R
B/WB/LLYP/BG/WB/R
R/BLg
Br/W
P
O
Y/GB/YP/LY/RSb
RR/B
RB/R
B/LBr/WB/L G/W
LYB/L
B/LP/BL
L LLRRRRRRRR
BBBBBB
B/L B/L B/L B/L B/L B/L
R O
OR

IGNITION SYSTEM
8-3
1. Crankshaft position sensor
2. AC magneto
3. Rectifier/regulator
4. Joint connector
5. Condenser
7. Engine stop switch
8. Neutral switch
9. Launch control switch
10.ECU
11.Ignition coil
12.Spark plug
19.Ignition coil sub-lead

IGNITION SYSTEM
8-4
EASB111321TROUBLESHOOTING
The ignition system fails to operate (no spark or intermittent spark).
TIP
Before troubleshooting, remove the following part(s):
1. Side cover (left/right)
2. Seat
3. Fuel tank
4. Air scoop (left/right)
5. Air filter case cover
1. Check the ignition system wire har-
ness connections.NG 
Reconnect.
OK 
2. Check the spark plug.
Refer to “CHECKING THE SPARK
PLUG” on page 3-37.NG 
Correct or replace the spark plug.
OK 
3. Check the ignition spark gap.
Refer to “CHECKING THE IGNI-
TION SPARK GAP” on page 8-41.OK 
The ignition system circuit is OK.
NG 
4. Check the ignition coil.
Refer to “CHECKING THE IGNI-
TION COIL” on page 8-41.NG 
Replace the ignition coil.
OK 
5. Check the engine stop switch.
Refer to “CHECKING THE
SWITCHES” on page 8-38.NG 
Replace the engine stop switch.
OK 
6. Check the crankshaft position sen-
sor.
Refer to “CHECKING THE CRANK-
SHAFT POSITION SENSOR” on
page 8-42.NG 
Replace the crankshaft position sensor.
OK 
7. Check the stator coil.
Refer to “CHECKING THE STA-
TOR COIL” on page 8-42.NG 
Replace the stator coil.
OK 

IGNITION SYSTEM
8-5
The launch control indicator light fail to blink.
TIP
Before troubleshooting, remove the following part(s):
1. Seat
2. Air scoop (left)8. Check the ignition system wire har-
ness.
Refer to “CIRCUIT DIAGRAM” on
page 8-2.NG 
Repair or replace the wire harness.
OK 
Replace the ECU.
1. Check the launch control switch
coupler connections.NG 
Reconnect.
OK 
2. Check the neutral switch coupler
connections.NG 
Reconnect.
OK 
3. Check the launch control switch.
Refer to “CHECKING THE
SWITCHES” on page 8-38.NG 
Replace the launch control switch.
OK 
4. Check the neutral switch.
Refer to “CHECKING THE NEU-
TRAL SWITCH” on page 8-46.NG 
Replace the neutral switch.
OK 
5. Check the fuel ignition system wire
harness.
Refer to “CIRCUIT DIAGRAM” on
page 8-2.NG 
Repair or replace the wire harness.
OK 
Replace the ECU.

CHARGING SYSTEM
8-6
EAS27200
CHARGING SYSTEM
EASB111322CIRCUIT DIAGRAM
ONOFF
ONOFF
B R
RRRRRRRR
BBBBBB
LLL
B/LB/LB/LB/LB/LB/L
B/L
Gy
W
W
W
W
R
R
B
B
B
B
RY/RY/G
Y/GY/B
Y/B
Y/W
Y/WB/YL/WB/R
B/Y
B/Y
B/W
R/B
R/B
B/R
B/R
G/WP/B
P/B
B/L
B/L
B/L
G/W
Br/W
Br/W
B/LB/L
B/W
Y/RSbP
Sb
Sb
P
P
P
L
L
LY
Y
B
B
LgGy
Lg
R
R
R
R
R
R
O
O
O
RO
WWW W
W W
W W
R B
B/LGyB Gy
BRRB
RLgB/W
B/YB
B B
PP/LSbSbY/WP
B RY/R Y/GBB/WWR/Y
BGy R
B/WB/LLYP/BG/WB/R
R/BLg
Br/W
P
O
Y/GB/YP/LY/RSb
RR/B
RB/R
B/LBr/WB/L G/W
LYB/L
B/LP/BL
L LLRRRRRRRR
BBBBBB
B/L B/L B/L B/L B/L B/L
R O
OR

CHARGING SYSTEM
8-7
2. AC magneto
3. Rectifier/regulator
4. Joint connector
5. Condenser

CHARGING SYSTEM
8-8
EASB111323TROUBLESHOOTING
The condenser is not being charged.
TIP
Before troubleshooting, remove the following part (s):
1. Seat
2. Air scoop (left)
1. Check the entire charging system’s
wiring.NG 
Reconnect.
OK 
2. Check the rectifier/regulator.
Refer to “CHECKING THE RECTI-
FIER/REGULATOR” on page 8-43.NG 
Replace the rectifier/regulator.
OK 
3. Check the stator coil.
Refer to “CHECKING THE STA-
TOR COIL” on page 8-42.NG 
Replace the stator coil.
OK 
4. Check the charging system wire
harness.
Refer to “CIRCUIT DIAGRAM” on
page 8-6.NG 
Repair or replace the wire harness.
OK 
Replace the condenser.