2014 YAMAHA YZ250F wiring

CHARGING SYSTEM
8-8
TROUBLE SHOOTING
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.

ELECTRICAL COMPONENTS
8-40
Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, check
the wiring connections and if necessary, replace the switch.
ECA14370
NOTICE
Never insert the tester probes into the coupler terminal slots “1”. Always insert the probes
from the opposite end of the coupler, taking care not to loosen or damage the leads.
TIP
• Before checking for continuity, set the pocket tester range to “ 1” to make a “0” adjustment.
• When checking for continuity, switch back and forth between the switch positions a few times.
Terminal connections of the switch are shown in the terminal connection diagram below.
The switch positions “a” are shown in the far left column and the switch lead colors are shown in the
top row in the switch illustration.
TIP
“ ” indicates continuity between switch terminals (i.e., a closed circuit at each switch posi-
tion).
The example illustration below shows that:
There is continuity between red and brown when the switch is “ON”.Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
a

TROUBLE SHOOTING
9-1
EAS1SM1350
TROUBLE SHOOTING
EAS1SM1351GENERAL INFORMATION
TIP
The following guide for troubleshooting does
not cover all the possible causes of trouble. It
should be helpful, however, as a guide to basic
troubleshooting. Refer to the relative procedure
in this manual for checks, adjustments, and re-
placement of parts.
EAS1SM1352STARTING FAILURES
Engine
1. Cylinder and cylinder head
• Loose spark plug
• Loose cylinder head or cylinder
• Damaged cylinder head gasket
• Damaged cylinder gasket
• Worn or damaged cylinder
• Incorrect valve clearance
• Improperly sealed valve
• Incorrect valve-to-valve-seat contact
• Incorrect valve timing
• Faulty valve spring
• Seized valve
2. Piston and piston ring(s)
• Improperly installed piston ring
• Damaged, worn or fatigued piston ring
• Seized piston ring
• Seized or damaged piston
3. Air filter
• Improperly installed air filter
• Clogged air filter element
4. Crankcase and crankshaft
• Improperly assembled crankcase
• Seized crankshaft
Fuel system
1. Fuel tank
• Empty fuel tank
• Clogged fuel tank breather hose
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose
2. Fuel pump
• Faulty fuel pump
3. Throttle body
• Deteriorated or contaminated fuel
• Sucked-in airElectrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
2. Ignition coil
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
4. Switches and wiring
• Faulty ECU
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty neutral switch
• Improperly grounded circuit
• Loose connections
EAS1SM1353INCORRECT ENGINE IDLING SPEED
Engine
1. Cylinder and cylinder head
• Incorrect valve clearance
• Damaged valve train components
2. Air filter
• Clogged air filter element
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
• Improperly synchronized throttle bodies
• Improper throttle cable free play
• Flooded throttle body
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
• Faulty spark plug cap
2. Ignition coil
• Broken or shorted primary or secondary
coils
• Cracked or broken ignition coil

EAS1SM1381
WIRING DIAGRAM
YZ250F 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 pressure sensor
EAS1SM1382COLOR 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
P/B Pink/Black
R/B Red/Black

A
A
A
A
B
R R R R R R RB
B
B
R
RRLgLg
B/W
B/YB/Y
B
B
B
PPPSb
B/L
P/B
P/B
Y
L
Y
L
L
G/W
Br/W
G/W
Br/WB/L
B/L
B/L
B/L
B/RB/R
R/BR/B
O
O
R
O
R
O
R
R
R
Sb
B
Gy
R
B/W
P
LB/L
B/L Gy B/L B/L B/L B/L B/L
L L
P P
B B B B
4
1
32
5
\f
7
8
10
\b
12
11
13
14
15
1\f
17
P P
Sb
R B
B/RR
RB
B/LGyBR
B/Y PSb
B B
RR/B
L YB/L
B/W RLg
B/LBr/W
B/L P/B L
B/LG/W
BB/Y
B
B/L B/L B/L B/L B/L B/LB B B B R R
P P P L L LR R R R R
B
O P
Gy
R
B/Y SbP/B
R/B Lg B/RG/WBr/WB/L L Y
R BB/L
Gy
ROOR(BLACK) (BLACK)
B/W
WIRING DIAGRAM
YZ250F (E) 2014 SCHÉMA DE CÂBLAGE
YZ250F (E) 2014
SCHALTPLAN
YZ250F (E) 2014SCHEMA ELETTRICO
YZ250F (E) 2014
1SM-28199-30_W.D.indd 12013/09/03 11:24:21

A
A
A
A
B
(BLACK) (BLACK)
4
1
32
5
6
7
8
10
9
12
11
13
14
15
16
17
WIRING DIAGRAM
YZ250F (E) 2014 SCHÉMA DE CÂBLAGE
YZ250F (E) 2014
SCHALTPLAN
YZ250F (E) 2014SCHEMA ELETTRICO
YZ250F (E) 2014
1SM-28199-30_W.D.indd 22013/09/03 11:24:21