ad blue YAMAHA YZ250F 2015 User Guide

ELECTRICAL COMPONENTS
8-44
EAS1SM5344CHECKING THE COOLANT TEMPERATURE
SENSOR
1. Remove:
• Coolant temperature sensor
EWA14130
WARNING
• Handle the coolant temperature sensor
with special care.
• Never subject the coolant temperature
sensor to strong shocks. If the coolant
temperature sensor is dropped, replace it.
2. Check:
• Coolant temperature sensor resistance
Out of specification  Replace.
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a. Connect the pocket tester ( 1k/100) to
the coolant temperature sensor.
b. Immerse the coolant temperature sensor in
a container filled with coolant.
TIP
Make sure the coolant temperature sensor ter-
minals do not get wet.c. Place a thermometer in the coolant.
d. Slowly heat the coolant, and then let it cool
to the specified temperature indicated in the
table.
e. Check the coolant temperature sensor for
continuity at the temperatures indicated in
the table.
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EAS1SM5345CHECKING THE THROTTLE POSITION
SENSOR
1. Remove:
• Throttle position sensor
(from the throttle body)
EWA1DX1009
WARNING
• Handle the throttle position sensor with
special care.
• Never subject the throttle position sensor
to strong shocks. If the throttle position
sensor is dropped, replace it. Coolant temperature sensor re-
sistance
2.51–2.78 k at 20 °C (68 °F)
210–221  at 100 °C (212 °F)
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Green/White “1”
• Negative tester probe 
Black/Blue “2”12
G/W B/L
B/L G/W

ELECTRICAL COMPONENTS
8-45
2. Check:
• Throttle position sensor maximum resis-
tance
Out of specification  Replace.
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a. Connect the pocket tester ( 1k) to the
throttle position sensor.
b. Check the throttle position sensor maximum
resistance.
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3. Install:
• Throttle position sensor
TIP
When mounting the throttle position sensor, ad-
just its angle properly. Refer to “ADJUSTING
THE THROTTLE POSITION SENSOR” on
page 7-9.
EAS1SM5346
CHECKING THE THROTTLE POSITION
SENSOR INPUT VOLTAGE
1. Check:
• Throttle position sensor input voltage
Out of specification  Replace the ECU.
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a. Connect the test harness S-pressure sensor
(3P) to the throttle position sensor coupler
and the wire harness.
b. Connect the pocket tester (20 VDC) to the
test harness S-pressure sensor (3P).
c. Start the engine.
d. Measure the throttle position sensor input
voltage.
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Resistance
6.30 k
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Blue “1”
• Negative tester probe 
Black/Blue “2”
21
Throttle position sensor input
voltage
4–6 V
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Test harness S-pressure sensor
(3P)
90890-03207
YU-03207
• Positive tester probe 
Blue “1”
• Negative tester probe 
Black/Blue “2”
21

ELECTRICAL COMPONENTS
8-46
EAS1SM5347CHECKING THE INTAKE AIR PRESSURE
SENSOR
1. Check:
• Intake air pressure sensor output voltage
Out of specification  Replace.
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a. Connect the pocket tester (20 VDC) to the
intake air pressure sensor coupler (wire har-
ness side).
b. Start the engine.
c. Measure the intake air pressure sensor out-
put voltage.
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EAS1SM5348CHECKING THE INTAKE AIR TEMPERA-
TURE SENSOR
1. Remove:
• Intake air temperature sensor
(from the air filter case)
EWA1DX1010
WARNING
• Handle the intake air temperature sensor
with special care.
• Never subject the intake air temperature
sensor to strong shocks. If the intake air
temperature sensor is dropped, replace it.2. Check:
• Intake air temperature sensor resistance
Out of specification  Replace.
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a. Connect the pocket tester ( 1k/100) to
the intake air temperature sensor terminal.
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EAS1SM5349CHECKING THE NEUTRAL SWITCH
1. Remove:
• Neutral switch
2. Check:
• Neutral switch
Out of specification  Replace. Intake air pressure sensor output
voltage
3.57–3.71 V at 101.3 kPa
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Pink/Black “1”
• Negative tester probe 
Black/Blue “2”12
P/B
P/B
Intake air temperature sensor re-
sistance
290–390  at 80 °C (176 °F)
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Brown/White “1”
• Negative tester probe 
Black/Blue “2”
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
12

ELECTRICAL COMPONENTS
8-47
EAS1SM5350CHECKING THE FUEL INJECTOR
1. Remove:
• Fuel injector
Refer to “THROTTLE BODY” on page 7-5.
2. Check:
• Fuel injector resistance
Out of specification  Replace.
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a. Disconnect the fuel injector coupler from the
fuel injector.
b. Connect the pocket tester ( 10) to the
fuel injector coupler.c. Measure the fuel injector resistance.
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Continuity
Positive tester probe 
Sky blue “1”
Negative tester probe 
Sensor terminal “a”
Continuity
Positive tester probe 
Black/Yellow “2”
Negative tester probe 
Sensor terminal “b”
Continuity
Positive tester probe 
Pink “3”
Negative tester probe 
Sensor terminal “b”
Fuel injector resistance
12.0 
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Injector terminal “1”
• Negative tester probe 
Injector terminal “2”
b ca
B/YP
Sb
2
13
12

CHASSIS
10-5
EAS1SM5378REAR SHOCK ABSORBER SETTING
PARTS
• Rear shock spring “1”
*Except for USA and CAN
TIP
• The I.D. mark “a” is marked at the end of the
spring.
• Spring specification varies according to the
color of I.D. marks.• Extent of adjustment (spring preload)
TIP
For the spring preload adjustment, refer to “AD-
JUSTING THE REAR SHOCK ABSORBER
ASSEMBLY” on page 3-30. TypeSpring
rate N/
mmPart numberI.D.
Mark
SOFT 521SL-22212-40
(Blue)
Yellow
1SL-22212-50
(Red)
STD* 541SL-22212-60
(Blue)
Pink
1SL-22212-70
(Red)
STD 561SL-22212-20
(Blue)
White
1SL-22212-30
(Red)
581SL-22212-00
(Blue)
Silver
1SL-22212-10
(Red)
STIFF 601SL-22212-80
(Blue)
Brown
1SL-22212-90
(Red)
Maximum Minimum
Position in which
the spring is turned
in 18 mm (0.71 in)
from its free length.Position in which
the spring is turned
in 1.5 mm (0.06 in)
from its free length.

EAS1SM5382
WIRING DIAGRAM
YZ250F/YZ250FF 2015
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
EAS1SM5383COLOR 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