engine YAMAHA WR 250F 2017 Owners Manual

9-1
EAS2GBB356
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
9-3
1. Joint connector
2. Joint connector
4. AC magneto
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
22.ECU (engine control unit)
23.Ignition coil
24.Spark plug
30.Joint connector
35.Lean angle sensor
36.Engine stop switch
48.Frame ground
49.Ignition coil sub-lead

IGNITION SYSTEM
9-4
EAS2GBB359TROUBLESHOOTING
The ignition system fails to operate (no spark or intermittent spark).
TIP
Before troubleshooting, remove the following part (s):
1. Seat
2. Side cover (left/right)
3. Air scoop (left/right)
4. Fuel tank
5. Air filter case cover
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 spark plug.
Refer to “CHECKING THE SPARK
PLUG” on page 3-40.NG 
Re-gap or replace the spark plug.
OK 
4. Check the ignition spark gap.
Refer to “CHECKING THE IGNI-
TION SPARK GAP” on page 9-73.OK 
The ignition system is normal.
NG 
5. Check the ignition coil.
Refer to “CHECKING THE IGNI-
TION COIL” on page 9-74.NG 
Replace the ignition coil.
OK 
6. Check the crankshaft position sen-
sor.
Refer to “CHECKING THE CRANK-
SHAFT POSITION SENSOR” on
page 9-75.NG 
Replace the stator assembly.
OK 
7. Check the engine stop switch.
Refer to “CHECKING THE
SWITCHES” on page 9-64.NG 
Replace the engine stop switch.
OK 

ELECTRIC STARTING SYSTEM
9-7
1. Joint connector
2. Joint connector
3. Joint connector
7. Main relay
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
13.Starter motor
14.Starter relay diode
22.ECU (engine control unit)
30.Joint connector
36.Engine stop switch
37.Neutral switch
38.Diode
39.Starting circuit cut-off relay
40.Clutch switch
41.Start switch
48.Frame ground

ELECTRIC STARTING SYSTEM
9-8
EAS2GBB361STARTING CIRCUIT CUT-OFF SYSTEM OPERATION
If the meter light comes on, the starter motor can only operate if at least one of the following condi-
tions is met:
• The transmission is in neutral (the neutral switch is closed).
• The clutch lever is pulled to the handlebar (the clutch switch is closed).
The starting circuit cut-off relay prevents the starter motor from operating when neither of these con-
ditions has been met. In this instance, the starting circuit cut-off relay is open so current cannot reach
the starter motor. When at least one of the above conditions has been met the starting circuit cut-off
relay is closed and the engine can be started by pressing the start switch.

ELECTRIC STARTING SYSTEM
9-11
8. Check the main relay.
Refer to “CHECKING THE RE-
LAYS” on page 9-72.NG 
Replace the main relay.
OK 
9. Check the neutral switch.
Refer to “CHECKING THE
SWITCHES” on page 9-64.NG 
Replace the neutral switch.
OK 
10.Check the clutch switch.
Refer to “CHECKING THE
SWITCHES” on page 9-64.NG 
Replace the clutch switch.
OK 
11.Check the engine stop switch.
Refer to “CHECKING THE
SWITCHES” on page 9-64.NG 
Replace the engine stop switch.
OK 
12.Check the start switch.
Refer to “CHECKING THE
SWITCHES” on page 9-64.NG 
Replace the start switch.
OK 
13.Check the entire starting system’s
wiring.
Refer to “CIRCUIT DIAGRAM” on
page 9-6.NG 
Properly connect or repair the starting sys-
tem’s wiring.
OK 
Replace the ECU.

LIGHTING SYSTEM
9-17
1. Joint connector
2. Joint connector
6. Headlight relay
7. Main relay
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
22.ECU (engine control unit)
30.Joint connector
42.Joint connector
43.Taillight
44.Headlight
47.Multi-function display
48.Frame ground

SIGNALING SYSTEM
9-21
1. Joint connector
2. Joint connector
3. Joint connector
7. Main relay
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
15.Indicator light
17.Fuel level warning light
18.Resistor
19.Fuel sender
22.ECU (engine control unit)
30.Joint connector
42.Joint connector
46.Speed sensor
47.Multi-function display
48.Frame ground

COOLING SYSTEM
9-25
1. Joint connector
2. Joint connector
3. Joint connector
7. Main relay
9. Battery
10.Frame ground
11.Starter relay
12.Main fuse
22.ECU (engine control unit)
27.Radiator fan motor relay
28.Radiator fan motor fuse
29.Radiator fan motor
30.Joint connector
32.Coolant temperature sensor
48.Frame ground

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