coolant temperature YAMAHA WR 250F 2017 User Guide

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
9-78
EAS2GBB397CHECKING THE RESISTER
1. Disconnect:
• Resister coupler
(from the wire harness)
2. Check:
• Resister resistance
Out of specification  Replace the resister.
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a. Connect the pocket tester ( 10) to the re-
sister as shown.
b. Measure the resistance of the resister.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GBB398CHECKING THE RADIATOR FAN MOTOR
1. Check:
• Radiator fan motor
Faulty/rough movement  Replace.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
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.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GBB399CHECKING 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.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester ( 1k/100) to
the coolant temperature sensor. Resister resistance
64.6–71.4 
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Black “1”
• Negative tester probe 
Black “2”
• Positive battery terminal 
Blue “1”
• Negative battery terminal 
Black “2”
1
2
Coolant temperature sensor re-
sistance
2512–2777  at 20 °C (2512–
2777  at 68 °F)
210–220  at 100 °C (210–220 
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
12V
LB

ELECTRICAL COMPONENTS
9-79
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.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GBB400CHECKING THE THROTTLE POSITION
SENSOR
1. Remove:
• Throttle position sensor
(from the throttle body)
EWA
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.
2. Check:
• Throttle position sensor maximum resis-
tance
Out of specification  Replace.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester ( 1k) to the
throttle position sensor.
b. Check the throttle position sensor maximum
resistance.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
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 8-11.
12
G/W B/L
B/L G/W
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

TROUBLESHOOTING
10-3
Cooling system
1. Coolant
• Low coolant level
2. Radiator
• Damaged or leaking radiator
• Faulty radiator cap
• Bent or damaged radiator fin
3. Water pump
• Damaged or faulty water pump
• Damaged hose
• Improperly connected hose
• Damaged pipe
• Improperly connected pipe
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
EAS2GBB416OVERCOOLING
Cooling system
1. Coolant temperature sensor
• Faulty coolant temperature sensor
EAS2GBB417POOR 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
EAS2GBB418FRONT 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
EAS2GBB419FAULTY 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
EAS2GBB420UNSTABLE 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

LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
10-5
EAS2GBB424
LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
LIST OF DIAGNOSTIC CODES
COMMUNICATION ERROR WITH YAMAHA DIAGNOSTIC TOOLFault
codeItem Page
12 Crankshaft position sensor: no normal signals are received from the
crankshaft position sensor.9-36
13 Intake air pressure sensor: open or short circuit detected. 9-37
14 Intake air pressure sensor: hose system malfunction (clogged or de-
tached hose)9-38
15 Throttle position sensor: open or short circuit detected. 9-39
16 Throttle position sensor: stuck throttle position sensor is detected. 9-41
21 Coolant temperature sensor: open or short circuit detected. 9-42
22 Intake air temperature sensor: open or short circuit detected. 9-43
30 Latch up detected. 9-44
33 Ignition coil: open or short circuit detected in the primary lead of the
ignition coil.9-45
39 Injector: open or short circuit detected. 9-47
41 Lean angle sensor: open or short circuit detected. 9-48
43 Fuel system voltage: incorrect voltage supplied to the fuel injector and
fuel pump.9-49
44 EEPROM fault code number: an error is detected while reading or
writing on EEPROM.9-50
46 Charging voltage is abnormal. 9-51
50 Faulty ECU memory. (When this malfunction is detected in the ECU,
the fault code number might not appear on the meter.)9-52
Fault
codeItem Page
Waiting
for con-
nectionNo communication signal is received from the ECU.
9-52
Er-2 Signals from the ECU cannot be received within the specified period
of time.9-53
Er-3 Data from the ECU cannot be received correctly. 9-54
Er-4 Registered data cannot be received from the Yamaha diagnostic tool. 9-55

LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS
10-6
SENSOR OPERATION TABLE
Diag-
nostic
code
No.Item Display Procedure
01 Throttle position sensor sig-
nal
• Fully closed position
• Fully opened position• 11–14
• 109–116• Check with throttle valve
fully closed.
• Check with throttle valve
fully open.
03 Intake air pressure Displays the intake air pres-
sure.Operate the throttle while
pushing the start switch. (If
the display value changes,
the performance is OK.)
05 Intake air temperature Displays the intake air tem-
perature.Compare the actually mea-
sured intake air tempera-
ture with the Yamaha
diagnostic tool display val-
ue.
06 Coolant temperature When engine is cold: Dis-
plays temperature closer to
air temperature.
When engine is hot: Displays
current coolant temperature.Compare the actually mea-
sured coolant temperature
with the Yamaha diagnostic
tool display value.
07 Vehicle speed pulses Vehicle speed pulse
0–999Check that the number in-
creases when the front
wheel is rotated. The num-
ber is cumulative and does
not reset each time the
wheel is stopped.
08 Lean angle sensor
• Upright
• OverturnedDisplays the output voltage.
• 0.4–1.4
• 3.7–4.4Remove the lean angle
sensor, and incline it more
than 45 degrees.
09 Monitor voltage Displays the fuel system volt-
age.
• Approximately 12.0 (V)—
21 Neutral switch
• Gear in neutral
• Gear not in neutral•ON
•OFFOperate the shift pedal.
60 EEPROM fault code display
• No fault
• CO adjustment value
• Setting tool adjustment
values 0–8 for fuel injec-
tion amount or ignition tim-
ing•00
•01
•07—
61 Malfunction history ( )
code display *1
• There is no history.
• There is some history.•00
• Other: Displays the fault
code of ( ).—

EAS2GBB426
WIRING DIAGRAM
WR250F/WR250FH 2017
1. Joint connector
2. Joint connector
3. Joint connector
4. AC magneto
5. Rectifier/regulator
6. Headlight relay
7. Main relay
8. Engine ground
9. Battery
10. Frame ground
11. Starter relay
12. Main fuse
13. Starter motor
14. Starter relay diode
15. Indicator light
16. Engine trouble warning light
17. Fuel level warning light
18. Resistor
19. Fuel sender
20. Diode
21. Coupler for connecting option-
al part
22. ECU (engine control unit)
23. Ignition coil
24. Spark plug
25. Injector
26. Fuel pump
27. Radiator fan motor relay
28. Radiator fan motor fuse
29. Radiator fan motor
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
41. Start switch
42. Joint connector
43. Taillight
44. Headlight
45. Coupler for connecting option-
al switch
46. Speed sensor
47. Multi-function display
48. Frame ground
49. Ignition coil sub-lead
50. Negative battery lead
EAS2GBB427
COLOR CODE
BBlack
Br Brown
Ch Chocolate
Dg Dark green
G Green
Gy Gray
LBlue
Lg Light green
O Orange
PPink
RRed
Sb Sky blue
WWhite
Y Yellow
B/L Black/Blue
B/O Black/Orange
B/W Black/White
B/Y Black/Yellow
Br/W Brown/White
G/B Green/Black
G/W Green/White
G/Y Green/Yellow
L/B Blue/Black
L/G Blue/Green
L/R Blue/Red
L/W Blue/White
L/Y Blue/Yellow
P/L Pink/Blue
R/B Red/Black
R/L Red/Blue
R/W Red/White
R/Y Red/Yellow
W/B White/Black
Y/B Yellow/Black
Y/G Yellow/Green
Y/R Yellow/Red