Yamaha Wr250r 2008 Manual

 
ELECTRICAL COMPONENTS 
8-70 
tery cool before reconnecting it. Hot
batteries can explode! 
 
As shown in the following illustration, the
open-circuit voltage of an MF battery stabi-
lizes about 30 minutes after charging has
been completed. Therefore, wait 30 min-
utes after charging is completed before 
measuring the open-circuit voltage.

 
Charging method using a variable-current
(voltage) charger 
a. Measure the open-circuit voltage prior to
charging.
NOTE:
 
Voltage...

 
ELECTRICAL COMPONENTS 
8-71 
6. Check: 
 
Battery terminals
Dirt  
→ 
 Clean with a wire brush.
Loose connection  
→ 
 Connect properly.
7. Install: 
 
Battery
8. Connect: 
 
Battery leads
(to the battery terminals)
9. Lubricate: 
 
Battery terminals
10.Install: 
 
Battery band
11.Install: 
 
Side cover (left)
Refer to “GENERAL CHASSIS” on page 4-1. 
EAS28040 
CHECKING THE RELAYS 
Check each switch for continuity with the pocket
tester. If the continuity reading is incorrect, re-
place the...

 
ELECTRICAL COMPONENTS 
8-72 
Headlight relay
Checking the turn signal relay

 
a. Check: 
 
Turn signal relay input voltage
Off specification  
→ 
Repair wire harness con-
nection failure from main switch to turn signal
relay coupler

 
a. Connect the pocket tester (DC 20 V) to the
turn signal relay terminal.b. Turn the main switch to “ON”.
c. Measure turn signal relay applied voltage.

 
d. Check: 
 
Turn...

 
ELECTRICAL COMPONENTS 
8-73 
Radiator fan motor relay 
EAS28050 
CHECKING THE DIODE 
1. Check: 
 
Diode
Out of specification  
→ 
 Replace.
NOTE:
 
The pocket tester and the analog pocket tester 
readings are shown in the following table.

 
a. Disconnect the starting circuit cut-off relay
from the wire harness.
b. Connect the pocket tester (  
Ω  
   
×  
 1) to the start-
ing circuit cut-off relay coupler as shown. 
1.  Positive battery terminal
2.  Negative battery...

 
ELECTRICAL COMPONENTS 
8-74 
c. Check the diode for continuity.
d. Check the diode for no continuity.

 
EAS28930 
CHECKING THE IGNITION SPARK GAP 
1. Check: 
 
Ignition spark gap
Out of specification  
→ 
 Perform the ignition
system troubleshooting, starting with step *.
Refer to “TROUBLESHOOTING” on page
8-3.
NOTE:
 
If the ignition spark gap is within specification, 
the ignition system circuit is operating normally.

 
a. Disconnect...

 
ELECTRICAL COMPONENTS 
8-75

 
a. Disconnect the spark plug cap from the igni-
tion coil.
b. Connect the pocket tester ( 
Ω 
  
× 
 1k) to the ig-
nition coil as shown.
c. Measure the secondary coil resistance.

 
EAS32D1002 
CHECKING THE CRANKSHAFT POSITION 
SENSOR 
1. Disconnect: 
 
Crankshaft position sensor coupler
(from the wire harness)
2. Check: 
 
Crankshaft position sensor resistance
Out of specification  
→ 
 Replace the...

 
ELECTRICAL COMPONENTS 
8-76 
c. Incline the lean angle sensor.
d. Measure the lean angle sensor out put volt-
age.

 
EAS28150 
CHECKING THE STATOR COIL 
1. Disconnect: 
 
Stator coil coupler
(from the wire harness)
2. Check: 
 
Stator coil resistance
Out of specification  
→ 
 Replace the stator coil.

 
a. Connect the pocket tester ( 
Ω 
  
× 
 1) to the stator
coil coupler as shown.b. Measure the stator coil resistance....

 
ELECTRICAL COMPONENTS 
8-77 
c. Start the engine and let it run at approximate-
ly 5000 r/min.
d. Measure the charging voltage.

 
EAS28180 
CHECKING THE HORN 
1. Check: 
 
Horn resistance
Out of specification  
→ 
 Replace.

 
a. Disconnect the horn leads from the horn ter-
minals.
b. Connect the pocket tester ( 
Ω 
  
× 
 1) to the horn
terminals.
c. Measure the horn resistance.

 
2. Check: 
 
Horn...

 
ELECTRICAL COMPONENTS 
8-78 
b. Set the main switch to “ON”.
c. Elevate the rear wheel and slowly turn it.
d. Measure the voltage (DC 5 V) of white and
black/blue. With the front wheel slowly rotat-
ing, voltage alternates between 0 V and 5 V.

 
EAS32D1012 
CHECKING THE FUEL SENDER (FUEL 
PUMP) 
Drain the gasoline.
1. Disconnect: 
 
Fuel pump coupler
(from the fuel pump)
2. Remove: 
 
Fuel pump
(from the fuel pump tank)
3. Check: 
 
Fuel sender resistance
Out of...

 
ELECTRICAL COMPONENTS 
8-79 
b. Immerse the coolant temperature sensor in a
container filled with coolant.
NOTE:
 
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 ta-
ble.
e. Check the coolant temperature sensor for
continuity at the temperatures indicated in
the table.

 
EAS28250 
CHECKING THE RADIATOR FAN MOTOR 
1....