YAMAHA YZ450F 2015 Owners Manual

8-1
EAS1SL5320
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
EAS1SL5321
IGNITION SYSTEM
EAS1SL5322CIRCUIT DIAGRAM
B/L Gy
BR
A
A
AA
B
RR R R R R R
B
B
B RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W P L B/L
B/L GyB/L B/L B/L B/L B/L LL PP BBBB
PP
Sb
RB
B/RR
R B
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
OP Gy
R
B/Y Sb
P/B
R/BLgB/RG/WBr/WB/L L Y
RB
B/LGy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17

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

IGNITION SYSTEM
8-4
EAS1SL5323TROUBLESHOOTING
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 3-35.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 8-43.NG 
Replace the stator coil.
OK 

IGNITION SYSTEM
8-5
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.

CHARGING SYSTEM
8-6
EAS27200
CHARGING SYSTEM
EAS1SL5324CIRCUIT DIAGRAM
B/L Gy
BR
A
A
AA
B
RR R R R R R
B
B
B RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W P L B/L
B/L GyB/L B/L B/L B/L B/L LL PP BBBB
PP
Sb
RB
B/RR
R B
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
OP Gy
R
B/Y Sb
P/B
R/BLgB/RG/WBr/WB/L L Y
RB
B/LGy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17

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

CHARGING SYSTEM
8-8
EAS1SL5325TROUBLESHOOTING
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 8-43.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.

CHARGING SYSTEM
8-9

FUEL INJECTION SYSTEM
8-10
EAS1SL5326
FUEL INJECTION SYSTEM
EAS1SL5327CIRCUIT DIAGRAM
B/L Gy
BR
A
A
AA
B
RR R R R R R
B
B
B RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W P L B/L
B/L GyB/L B/L B/L B/L B/L LL PP BBBB
PP
Sb
RB
B/RR
R B
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
OP Gy
R
B/Y Sb
P/B
R/BLgB/RG/WBr/WB/L L Y
RB
B/LGy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17