2016 YAMAHA WR 250F coolant temperature

COOLING SYSTEM
9-26
EAS2GB7371TROUBLESHOOTING
The radiator fan motor fails to turn.
TIP
Before troubleshooting, remove the following part(s):
1. Seat
2. Side cover (left)
3. Air scoop (left/right)
4. Fuel tank
1. Check the fuse.
Refer to “CHECKING THE FUSES”
on page 9-68.NG 
Replace the fuse(s).
OK 
2. Check the battery.
Refer to “CHECKING AND
CHARGING THE BATTERY” on
page 9-69.NG 
• Clean the battery terminals.
• Recharge or replace the battery.
OK 
3. Check the main relay.
Refer to “CHECKING THE RE-
LAYS” on page 9-72.NG 
Replace the main relay.
OK 
4. Check the radiator fan motor.
Refer to “CHECKING THE RADIA-
TOR FAN MOTOR” on page 9-78.NG 
Replace the radiator fan motor.
OK 
5. Check the radiator fan motor relay.
Refer to “CHECKING THE RE-
LAYS” on page 9-72.NG 
Replace the radiator fan motor relay.
OK 
6. Check the coolant temperature sen-
sor.
Refer to “CHECKING THE COOL-
ANT TEMPERATURE SENSOR”
on page 9-78.NG 
Replace the coolant temperature sensor.
OK 
7. Check the entire cooling system’s
wiring.
Refer to “CIRCUIT DIAGRAM” on
page 9-16.NG 
Properly connect or repair the cooling sys-
tem’s wiring.
OK 
Replace the ECU.

FUEL INJECTION SYSTEM
9-29
1. Joint connector
2. Joint connector
3. Joint connector
4. AC magneto
7. Main relay
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
15.Indicator light
16.Engine trouble warning light
22.ECU (engine control unit)
25.Injector
30.Joint connector
31.Intake air temperature sensor
32.Coolant temperature sensor
33.Throttle position sensor
34.Intake air pressure sensor
35.Lean angle sensor
36.Engine stop switch
37.Neutral switch
38.Diode
39.Starting circuit cut-off relay
40.Clutch switch
42.Joint connector
48.Frame ground

FUEL INJECTION SYSTEM
9-42
TIP
• Make sure that the engine is completely cool before checking the coolant temperature sensor.
• Before troubleshooting, disconnect the starter motor lead from the starter relay.
Fault code No. 21
Item Coolant temperature sensor: open or short circuit detected.
Fail-safe systemAble to start engine
Able to drive vehicle
Diagnostic code No.06
Diagnostic tool displayDisplays the coolant temperature.
ProcedureCompare the actually measured coolant temperature with the
Yamaha diagnostic tool display value.
ItemProbable cause of malfunc-
tion and checkMaintenance jobConfirmation of service
completion
1 Connection of coolant tem-
perature sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 2.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 3.
3 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
Between coolant temperature
sensor coupler and ECU cou-
pler.
green/white–green/white
black/blue–black/bluePush the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 4.
4 Installed condition of coolant
temperature sensor.
Check for looseness or
pinching.Improperly installed sensor
 Reinstall or replace the
sensor.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 5.

FUEL INJECTION SYSTEM
9-43
TIP
• Make sure that the engine is completely cool before checking the intake air temperature sensor.
• Before troubleshooting, disconnect the starter motor lead from the starter relay. 5 Defective coolant tempera-
ture sensor.Execute the diagnostic mode.
(Code No. 06)
When engine is cold:
Displayed temperature is
close to the ambient temper-
ature.
The displayed temperature is
not close to the ambient tem-
perature.  Check the cool-
ant temperature sensor.
Replace if defective.
Refer to “CHECKING THE
COOLANT TEMPERATURE
SENSOR” on page 9-78.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 6.
6 Malfunction in ECU. Replace the ECU.
Fault code No. 22
Item Intake air temperature sensor: open or short circuit detected.
Fail-safe systemAble to start engine
Able to drive vehicle
Diagnostic code No.05
Diagnostic tool displayDisplays the intake air temperature.
ProcedureCompare the actually measured intake air temperature with the
Yamaha diagnostic tool display value.
ItemProbable cause of malfunc-
tion and checkMaintenance jobConfirmation of service
completion
1 Connection of intake air tem-
perature sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 2.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler and
check the pins (bent or bro-
ken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler securely
or repair/replace the wire har-
ness.Push the start switch.
Fault code number is not dis-
played  Service is finished.
Fault code number is dis-
played  Go to item 3. Fault code No. 21
Item Coolant temperature sensor: open or short circuit detected.

ELECTRICAL COMPONENTS
9-63
1. Intake air temperature sensor
2. Intake air pressure sensor
3. Throttle position sensor
4. Starter relay
5. Main fuse
6. Headlight relay
7. Starting circuit cut-off relay
8. Lean angle sensor
9. Radiator fan motor fuse
10.Radiator fan motor relay
11.Main relay
12.Coolant temperature sensor

ELECTRICAL COMPONENTS
9-75
Out of specification  Replace.
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a. Connect the pocket tester ( 100) to the
crankshaft position sensor coupler.
b. Measure the crankshaft position sensor re-
sistance.
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EAS2GB7392CHECKING THE LEAN ANGLE SENSOR
1. Remove:
• Lean angle sensor
(from the bracket)
2. Check:
• Lean angle sensor output voltage
Out of specification  Replace.
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a. Connect the lean angle sensor coupler to
the wire harness.
b. Connect the pocket tester (DC 20 V) to the
lean angle sensor coupler as shown.c. Incline the lean angle sensor.
d. Measure the lean angle sensor output volt-
age.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GB7393CHECKING THE STARTER MOTOR OPERA-
TION
1. Check:
• Coolant temperature sensor
Does not operate  Perform the electric
starting system troubleshooting, starting
with step 4.
Refer to “ELECTRIC STARTING SYSTEM”
on page 9-6.
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a. Connect the positive battery terminal “1” and
starter motor lead “2” with a jumper lead “3”.
EWA
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. Crankshaft position sensor resis-
tance
228–342  (Gy–B)
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Gray “1”
• Negative tester probe 
Black “2”
Lean angle sensor output voltage
Less than 45° “a”
0.4–1.4V
More than 45° “b”
3.7–4.4V
12
Gy B
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Test harness– lean angle sensor
(6P)
90890-03209
Test harness– lean angle sensor
(6P)
YU-03209
• Positive tester probe 
Yellow/Green “1”
• Negative tester probe 
Black/Blue “2”
2 1
aa
bON ON

ELECTRICAL COMPONENTS
9-78
b. Measure the resistance of the resister.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS2GB7398CHECKING THE RADIATOR FAN MOTOR
1. Check:
• Radiator fan motor
Faulty/rough movement  Replace.
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a. Disconnect the radiator fan motor coupler
from the wire harness.
b. Connect the battery (DC 12 V) as shown.
c. Measure the radiator fan motor movement.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GB7399CHECKING THE COOLANT TEMPERATURE
SENSOR
1. Remove:
• Coolant temperature sensor
EWA
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. • Positive tester probe 
Black “1”
• Negative tester probe 
Black “2”
• Positive battery terminal 
Blue “1”
• Negative battery terminal 
Black “2”
1
2
12
12V
LB
Coolant temperature sensor re-
sistance
2.51–2.78 k at 20 °C (2.51–2.78
k at 68 °F)
210–221  at 100 °C (210–221 
at 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

TROUBLESHOOTING
10-3
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
EAS2GB7416OVERCOOLING
Cooling system
1. Coolant temperature sensor
• Faulty coolant temperature sensor
EAS2GB7417POOR BRAKING PERFORMANCE
Chassis
1. Brake(s)
• 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
EAS2GB7418FRONT FORK OIL LEAKING
Chassis
1. Front fork
• 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
EAS2GB7419FAULTY FRONT FORK LEGS
Chassis
1. Front fork
• Bent or damaged inner tube
• Bent or damaged outer tube
• Broken fork spring
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EAS2GB7420UNSTABLE HANDLING
Chassis
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