Yamaha XV19SW(C), XV19W(C), XV19MW(C), XV19CTSW(C), XV19CTW(C), XV19CTMW(C). Service Manual - part 27

ELECTRICAL COMPONENTS

7-76

cal system, cause the lighting and ignition 
systems to malfunction and could possibly 
cause a fire.

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4. Install:

• Rider seat

Refer to “GENERAL CHASSIS” on page 4-1.

EAS28030

CHECKING AND CHARGING THE BATTERY

WARNING

EWA13290

Batteries generate explosive hydrogen gas 
and contain electrolyte which is made of poi-
sonous and highly caustic sulfuric acid. 
Therefore, always follow these preventive 
measures:
• Wear protective eye gear when handling or 

working near batteries.

• Charge batteries in a well-ventilated area.
• Keep batteries away from fire, sparks or 

open flames (e.g., welding equipment, 
lighted cigarettes).

• DO NOT SMOKE when charging or han-

dling batteries.

• KEEP BATTERIES AND ELECTROLYTE 

OUT OF REACH OF CHILDREN.

• Avoid bodily contact with electrolyte as it 

can cause severe burns or permanent eye 
injury.

FIRST AID IN CASE OF BODILY CONTACT:
EXTERNAL
• Skin — Wash with water.
• Eyes — Flush with water for 15 minutes and 

get immediate medical attention.

INTERNAL
• Drink large quantities of water or milk fol-

lowed with milk of magnesia, beaten egg or 
vegetable oil. Get immediate medical atten-
tion.

CAUTION:

EC1D71020

• This is a sealed battery. Never remove the 

sealing caps because the balance between 
cells will not be maintained and battery per-
formance will deteriorate.

• Charging time, charging amperage and 

charging voltage for an MF battery are dif-
ferent from those of conventional batteries. 
The MF battery should be charged accord-
ing to the instructions for the charging 
method. If the battery is overcharged, the 

electrolyte level will drop considerably. 
Therefore, take special care when charging 
the battery.

NOTE:

Since MF batteries are sealed, it is not possible 
to check the charge state of the battery by mea-
suring the specific gravity of the electrolyte. 
Therefore, the charge of the battery has to be 
checked by measuring the voltage at the battery 
terminals.

1. Remove:

• Rider seat

Refer to “GENERAL CHASSIS” on page 4-1.

2. Remove:

• ECU band “1”

3. Remove:

• Coupler tray “1”

4. Disconnect:

• Battery leads

(from the battery terminals)

CAUTION:

ECA13640

First, disconnect the negative battery lead 
“1”, and then positive battery lead “2”.

1

1

ELECTRICAL COMPONENTS

7-77

5. Remove:

• Battery

6. Check:

• Battery charge

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a. Connect a pocket tester to the battery termi-

nals.

NOTE:

• The charge state of an MF battery can be 

checked by measuring its open-circuit voltage 
(i.e., the voltage when the positive battery ter-
minal is disconnected).

• No charging is necessary when the open-cir-

cuit voltage equals or exceeds 12.8 V.

b. Check the charge of the battery, as shown in 

the charts and the following example.

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7. Charge:

• Battery

(refer to the appropriate charging method il-
lustration)

WARNING

EWA13300

Do not quick charge a battery.

CAUTION:

ECA13670

• Never remove the MF battery sealing caps.
• Do not use a high-rate battery charger 

since it forces a high-amperage current 
into the battery quickly and can cause bat-
tery overheating and battery plate damage.

• If it is impossible to regulate the charging 

current on the battery charger, be careful 
not to overcharge the battery.

• When charging a battery, be sure to remove 

it from the vehicle. (If charging has to be 
done with the battery mounted on the vehi-
cle, disconnect the negative battery lead 
from the battery terminal.)

• To reduce the chance of sparks, do not 

plug in the battery charger until the battery 
charger leads are connected to the battery.

• Before removing the battery charger lead 

clips from the battery terminals, be sure to 
turn off the battery charger.

• Make sure the battery charger lead clips are 

in full contact with the battery terminal and 
that they are not shorted. A corroded bat-
tery charger lead clip may generate heat in 
the contact area and a weak clip spring may 
cause sparks.

• Positive tester probe 

→

positive battery terminal

• Negative tester probe 

→

negative battery terminal

Example
Open-circuit voltage = 12.0 V
Charging time = 6.5 hours
Charge of the battery = 20–30%

A. Open-circuit voltage (V)
B. Charging time (hours)
C. Relationship between the open-circuit voltage 

and the charging time at 20 °C (68 °F)

D. These values vary with the temperature, the 

condition of the battery plates, and the 
electrolyte level.

1

2

A. Open-circuit voltage (V)
B. Charging condition of the battery (%)
C. Ambient temperature 20 °C (68 °F)

ELECTRICAL COMPONENTS

7-78

• If the battery becomes hot to the touch at 

any time during the charging process, dis-
connect the battery charger and let the bat-
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.

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Charging method using a variable-current 
(voltage) charger

a. Measure the open-circuit voltage prior to 

charging.

NOTE:

Voltage should be measured 30 minutes after 
the engine is stopped.

b. Connect a charger and ammeter to the bat-

tery and start charging.

NOTE:

Set the charging voltage at 16–17 V. If the set-
ting is lower, charging will be insufficient. If too 
high, the battery will be over-charged.

c. Make sure that the current is higher than the 

standard charging current written on the bat-
tery.

NOTE:

If the current is lower than the standard charging 
current written on the battery, set the charging 
voltage adjust dial at 20–24 V and monitor the 
amperage for 3–5 minutes to check the battery.

d. Adjust the voltage so that the current is at the 

standard charging level.

e. Set the time according to the charging time 

suitable for the open-circuit voltage.

f. If charging requires more than 5 hours, it is 

advisable to check the charging current after 
a lapse of 5 hours. If there is any change in 
the amperage, readjust the voltage to obtain 
the standard charging current.

g. Measure the battery open-circuit voltage after 

leaving the battery unused for more than 30 
minutes.

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Charging method using a constant volt-
age charger

a. Measure the open-circuit voltage prior to 

charging.

NOTE:

Voltage should be measured 30 minutes after 
the engine is stopped.

b. Connect a charger and ammeter to the bat-

tery and start charging.

c. Make sure that the current is higher than the 

standard charging current written on the bat-
tery.

NOTE:

If the current is lower than the standard charging 
current written on the battery, this type of battery 
charger cannot charge the MF battery. A vari-
able voltage charger is recommended.

d. Charge the battery until the battery’s charg-

ing voltage is 15 V.

NOTE:

Set the charging time at 20 hours (maximum).

e. Measure the battery open-circuit voltage after 

leaving the battery unused for more than 30 
minutes.

A. Open-circuit voltage (V)
B. Time (minutes)
C. Charging
D. Ambient temperature 20 °C (68 °F)
E. Check the open-circuit voltage.

• Standard charging current is reached

Battery is good.

• Standard charging current is not reached

Replace the battery.

12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.

ELECTRICAL COMPONENTS

7-79

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8. Install:

• Battery

9. Connect:

• Battery leads

(to the battery terminals)

CAUTION:

ECA13630

First, connect the positive battery lead “1”, 
and then the negative battery lead “2”.

NOTE:

Be sure to route the negative battery lead to-
wards the front of the vehicle and to install the 
negative terminal cover “3” securely.

10.Check:

• Battery terminals

Dirt 

→

 Clean with a wire brush.

Loose connection 

→

 Connect properly.

11.Lubricate:

• Battery terminals

12.Install:

• Coupler tray
• ECU band

NOTE:

Make sure the leads are routed correctly.

13.Install:

• Rider seat

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 relay.

1. Disconnect the relay from the wire harness.
2. Connect the pocket tester (

Ω

 

×

 1) and battery 

(12 V) to the relay terminals as shown.
Check the relay operation.
Out of specification 

→

 Replace.

Starter relay

Relay unit (starting circuit cut-off relay)

12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.

 

Recommended lubricant

Dielectric grease

3

1

2

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe

 

Result

Continuity

(between “3” and “4”)

1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe

 

Result

Continuity

(between “3” and “4”)

R

B

R

R

/

Y

L

2

1

4

3

+

3

1

2

4

ELECTRICAL COMPONENTS

7-80

Relay unit (fuel pump relay)

Headlight relay

ET1D71011

CHECKING THE TURN SIGNAL RELAY

1. Check:

• Turn signal relay input voltage

Out of specification 

→

 The wiring circuit from 

the main switch to the turn signal relay cou-
pler is faulty and must be repaired.

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a. Connect the pocket tester (DC 20 V) to the 

turn signal relay terminal as shown.

b. Turn the main switch to “ON”.
c. Measure the turn signal relay input voltage.

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2. Check:

• Turn signal relay output voltage

Out of specification 

→

 Replace.

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a. Connect the pocket tester (DC 20 V) to the 

turn signal relay terminal as shown.

1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe

 

Result

Continuity

(between “3” and “4”)

1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe

 

Result

Continuity

(between “3” and “4”)

 

Turn signal relay input voltage

DC 12 V

+

3

1

2

4

+

R

/

Y

G

/

L

Br

Y

/

B

1

2

3

4

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

brown “1”

• Negative tester probe 

→

ground

 

Turn signal relay output voltage

DC 12 V

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

brown/white “1”, yellow/red “2” or white/yel-
low “3”

• Negative tester probe 

→

ground

ELECTRICAL COMPONENTS

7-81

b. Turn the main switch to “ON”.
c. Measure the turn signal relay output voltage.

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EAS28050

CHECKING THE DIODES

Relay unit (diode)

1. Check:

• Relay unit (diode)

Out of specification 

→

 Replace.

NOTE:

The pocket tester or the analog pocket tester 
readings are shown in the following table.

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a. Disconnect the relay unit from the wire har-

ness.

b. Connect the pocket tester (

Ω

 

×

 1) to the relay 

unit terminals as shown.

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

 

Continuity

Positive tester probe 

→

 sky blue 

“1”
Negative tester probe 

→

 

black/yellow “2”

No continuity

Positive tester probe 

→

 

black/yellow “2”
Negative tester probe 

→

 sky 

blue “1”

Continuity

Positive tester probe 

→

 sky blue 

“1”
Negative tester probe 

→

 

blue/yellow “3”

No continuity

Positive tester probe 

→

 

blue/yellow “3”
Negative tester probe 

→

 sky 

blue “1”

Continuity

Positive tester probe 

→

 sky blue 

“1”
Negative tester probe 

→

 sky 

blue/white “4”

No continuity

Positive tester probe 

→

 sky 

blue/white “4”
Negative tester probe 

→

 sky 

blue “1”

Continuity

Positive tester probe 

→

 

blue/green “5”
Negative tester probe 

→

 

blue/yellow “3”

No continuity

Positive tester probe 

→

 

blue/yellow “3”
Negative tester probe 

→

 

blue/green “5”

3

5

1

2 4

ELECTRICAL COMPONENTS

7-82

c. Check the relay unit (diode) for continuity.
d. Check the relay unit (diode) for no continuity.

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Diode 1

1. Check:

• Diode 1

Out of specification 

→

 Replace.

NOTE:

The pocket tester and the analog pocket tester 
readings are shown in the following table.

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a. Disconnect the diode 1 from the wire har-

ness.

b. Connect the pocket tester (

Ω

 

×

 1) to the diode 

1 terminals as shown.

c. Check the diode 1 for continuity.
d. Check the diode 1 for no continuity.

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Diode 2

1. Check:

• Diode 2

Out of specification 

→

 Replace.

NOTE:

The pocket tester and the analog pocket tester 
readings are shown in the following table.

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a. Disconnect the diode 2 from the wire har-

ness.

b. Connect the pocket tester (

Ω

 

×

 1) to the diode 

2 terminals as shown.

c. Check the diode 2 for continuity.
d. Check the diode 2 for no continuity.

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ET1D71012

CHECKING THE IGNITION SPARK GAP

1. Check:

• Ignition spark gap

Out of specification 

→

 Perform the ignition 

system troubleshooting, starting with step 5.
Refer to “TROUBLESHOOTING” on page 
7-4.

NOTE:

If the ignition spark gap is within specification, 
the ignition system circuit is operating normally.

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

 

Continuity

Positive tester probe 

→

 red/yel-

low “1”
Negative tester probe 

→

 

red/white “2” or red/white “3”

No continuity

Positive tester probe 

→

 

red/white “2” or red/white “3”
Negative tester probe 

→

 red/yel-

low “1”

R

/

W R

/

W

R

/

Y

2

3

1

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

 

Continuity

Positive tester probe 

→

 

red/white “1”
Negative tester probe 

→

 

black/red “2”

No continuity

Positive tester probe 

→

 

black/red “2”
Negative tester probe 

→

 

red/white “1”

 

Minimum ignition spark gap

6.0 mm (0.24 in)

1

2

R

/

W

B

/

R

ELECTRICAL COMPONENTS

7-83

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a. Disconnect the spark plug cap from the spark 

plug.

b. Connect the ignition checker “1” as shown.

c. Turn the main switch to “ON” and engine stop 

switch to “

”.

d. Measure the ignition spark gap “a”.
e. Crank the engine by pushing the start switch 

“

” and gradually increase the spark gap un-

til a misfire occurs.

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EAS28070

CHECKING THE SPARK PLUG CAPS

The following procedure applies to all of the 
spark plug caps.
1. Check:

• Spark plug cap resistance

Out of specification 

→

 Replace.

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a. Remove the spark plug cap from the spark 

plug lead.

b. Connect the pocket tester (

Ω

 

×

 1k) to the 

spark plug cap as shown.

c. Measure the spark plug cap resistance.

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EAS28100

CHECKING THE IGNITION COILS

The following procedure applies to all of the igni-
tion coils.
1. Check:

• Primary coil resistance

Out of specification 

→

 Replace.

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a. Disconnect the ignition coil connectors from 

the ignition coil terminals.

b. Connect the pocket tester (

Ω

 

×

 1) to the igni-

tion coil as shown.

c. Measure the primary coil resistance.

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2. Check:

• Secondary coil resistance

Out of specification 

→

 Replace.

 

Ignition checker

90890-06754

Opama pet-4000 spark checker

YM-34487

2. Spark plug cap

 

Resistance

10.0 k

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

 

Primary coil resistance

2.16–2.64 

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

black/red “1”

• Negative tester probe 

→

orange or gray/red “2”

ELECTRICAL COMPONENTS

7-84

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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.

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EAS28120

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 crank-

shaft position sensor.

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a. Connect the pocket tester (

Ω

 

×

 100) to the 

crankshaft position sensor coupler as shown.

b. Measure the crankshaft position sensor re-

sistance.

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EAS28130

CHECKING THE LEAN ANGLE SENSOR

1. Remove:

• Lean angle sensor

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.

 

Secondary coil resistance

8.64–12.96 k

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Negative tester probe 

→

black/red “1”

• Positive tester probe 

→

spark plug lead “2”

 

Crankshaft position sensor resis-
tance

248–372 

Ω

 

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 65°: 0.4–1.4 V
More than 65°: 3.7–4.4 V

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

yellow/green “1”

• Negative tester probe 

→

black/blue “2”

Gy

B

1

2

ELECTRICAL COMPONENTS

7-85

c. Turn the lean angle sensor to 65°.
d. Measure the lean angle sensor output volt-

age.

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ET1D71013

CHECKING THE STARTER MOTOR 
OPERATION

1. Check:

• Starter motor operation

Does not operate 

→

 Perform the electric 

starting system troubleshooting, starting with 
step 5.
Refer to “TROUBLESHOOTING” on page 
7-11.

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a. Connect the positive battery terminal “1” and 

starter motor lead “2” with a jumper lead “3”.

WARNING

EWA13810

• A wire that is used as a jumper lead must 

have at least the same capacity of the bat-
tery lead, otherwise the jumper lead may 
burn.

• This check is likely to produce sparks, 

therefore, make sure no flammable gas or 
fluid is in the vicinity.

b. Check the starter motor operation.

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EAS28150

CHECKING THE STATOR COIL

1. Disconnect:

• Stator coil coupler

(from the rectifier/regulator)

2. Check:

• Stator coil resistance

Out of specification 

→

 Replace the stator coil.

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a. Connect the pocket tester (

Ω

 

×

 1) to the stator 

coil coupler as shown.

b. Measure the stator coil resistance.

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EAS28170

CHECKING THE RECTIFIER/REGULATOR

1. Check:

• Charging voltage

Out of specification 

→

 Replace the rectifi-

er/regulator.

 

Stator coil resistance

0.112–0.168 

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

white “1”

• Negative tester probe 

→

white “2”

• Positive tester probe 

→

white “1”

• Negative tester probe 

→

white “3”

• Positive tester probe 

→

white “2”

• Negative tester probe 

→

white “3”

W

W

W

2 3

1

ELECTRICAL COMPONENTS

7-86

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a. Set the engine tachometer to the cylinder-#1 

left spark plug lead or right spark plug lead.

b. Connect the pocket tester (DC 20 V) to the 

rectifier/regulator coupler as shown.

c. Start the engine and let it run at approximate-

ly 5000 r/min.

d. Measure the charging voltage.

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EAS28180

CHECKING THE HORNS

1. Check:

• Horn resistance

Out of specification 

→

 Replace.

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a. Disconnect the horn 1 connectors and horn 2 

coupler from the horn terminals.

b. Connect the pocket tester (

Ω

 

×

 1) to the horn 

terminals.

c. Measure the horn resistance.

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2. Check:

• Horn sound

Faulty sound 

→

 Adjust or replace.

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a. Connect a battery (12 V) to the horn.
b. Turn the adjusting screw in direction “a” or “b” 

until the horn sound is obtained.

 

Charging voltage

14 V at 5000 r/min

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

red “1”

• Negative tester probe 

→

black “2”

 

Coil resistance

0.94–0.98 

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

W

W W

2

1

B

R

• Positive tester probe 

→

horn terminal “1”

• Negative tester probe 

→

horn terminal “2”

A. Horn 1
B. Horn 2

1

2

A

1

2

B

ELECTRICAL COMPONENTS

7-87

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EAS28210

CHECKING THE ENGINE TEMPERATURE 
SENSOR

1. Remove:

• Engine temperature sensor

(from the front cylinder head)

WARNING

EWA14140

• Handle the engine temperature sensor with 

special care.

• Never subject the engine temperature sen-

sor to strong shocks. If the engine temper-
ature sensor is dropped, replace it.

2. Check:

• Engine temperature sensor resistance

Out of specification 

→

 Replace.

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a. Connect the pocket tester (

Ω

 

×

 1 k) to the en-

gine temperature sensor terminals as shown.

b. Immerse the engine temperature sensor “1” 

in a container filled with water “2”.

NOTE:

Make sure that the engine temperature sensor 
terminals do not get wet.

c. Place a thermometer “3” in the water.
d. Slowly heat the water, then let it cool down to 

the specified temperature.

e. Measure the engine temperature sensor re-

sistance.

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3. Install:

• Engine temperature sensor

ET1D71014

CHECKING THE FUEL SENDER (FUEL 
TANK)

1. Remove:

• Fuel sender

(from the fuel tank)

2. Check:

• Fuel sender resistance

Out of specification 

→

 Replace.

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a. Connect the pocket tester (

Ω

 

×

 100) to the 

fuel sender coupler as shown.

A. Horn 1
B. Horn 2

 

Engine temperature sensor resis-
tance

0.90–1.10 k

Ω

 at 100 °C (212 °F)

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

a

b

A

a

b

B

T

 

R

.

 

Engine temperature sensor

20 Nm (2.0 m·kg, 14 ft·lb)

 

Fuel sender (fuel tank)

Sender unit resistance (full)

9–11 

Ω

Sender unit resistance (empty)

213–219 

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

3

1

2

ELECTRICAL COMPONENTS

7-88

b. Move the fuel sender float to maximum 

“3”/minimum “4” level position.

c. Measure the fuel sender resistance.

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ET1D71015

CHECKING THE FUEL SENDER (FUEL 
PUMP)

1. Drain the fuel.
2. Disconnect:

• Fuel pump coupler

(from the fuel pump)

3. Remove:

• Fuel pump

(from the sub-fuel tank)

4. Check:

• Fuel sender resistance

Out of specification 

→

 Replace the fuel pump 

assembly.

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a. Connect the pocket tester (

Ω

 

×

 1) to the fuel 

sender terminals as shown.

b. Measure the fuel sender resistance.

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ET1D71044

CHECKING THE FUEL LEVEL WARNING 
LIGHT

This model is equipped with a self-diagnosis de-
vice for the fuel level detection circuit.
1. Check:

• Fuel level warning light “1”

(Turn the main switch to “ON”.)
Warning light comes on for a few seconds, 
then goes off 

→

 Warning light is OK.

Warning light does not come on 

→

 Replace 

the meter assembly.
Warning light flashes eight times, then goes 
off for three seconds in a repeated cycle (mal-
function detected in fuel sender or thermistor) 

→

 Replace the fuel pump assembly.

EAS28240

CHECKING THE SPEED SENSOR

1. Check:

• Speed sensor output voltage

Out of specification 

→

 Replace.

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a. Connect the pocket tester (DC 20 V) to the 

speed sensor coupler as shown.

• Positive tester probe 

→

green “1”

• Negative tester probe 

→

black “2”

 

Fuel sender resistance

0.90–2.05 k

Ω

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

green/white “1”

• Negative tester probe 

→

black “2”

G

B

3

1

2

4

 

Output voltage reading cycle

0.6 V to 4.8 V to 0.6 V to 4.8 V

R

/

L

G

/

W

B

B

2

1

1

ELECTRICAL COMPONENTS

7-89

b. Turn the main switch to “ON”.
c. Elevate the rear wheel and slowly rotate it.
d. Measure the voltage of white and black. With 

each full rotation of the rear wheel, the volt-
age reading should cycle from 0.6 V to 4.8 V 
to 0.6 V to 4.8 V.

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EAS28300

CHECKING THE THROTTLE POSITION 
SENSOR

1. Remove:

• Throttle position sensor

(from the throttle body)

2. Check:

• Throttle position sensor maximum resistance

Out of specification 

→

 Replace the throttle 

position sensor.

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a. Connect the pocket tester (

Ω

 

×

 1k) to the 

throttle position sensor terminals as shown.

b. Measure the throttle position sensor maxi-

mum resistance.

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3. Install:

• Throttle position sensor

NOTE:

When installing the throttle position sensor, ad-
just its angle properly. Refer to “ADJUSTING 
THE THROTTLE POSITION SENSOR” on page 
6-12.

EAS28350

CHECKING THE FUEL PUMP

WARNING

EWA13850

Gasoline is extremely flammable and under 
certain circumstances there can be a danger 
of an explosion or fire. Be extremely careful 
and note the following points:
• Stop the engine before refueling.
• Do not smoke, and keep away from open 

flames, sparks, or any other source of fire.

• If you do accidentally spill gasoline, wipe it 

up immediately with dry rags.

• If gasoline touches the engine when it is 

hot, a fire may occur. Therefore, make sure 
the engine is completely cool before per-
forming the following test.

1. Disconnect:

• Fuel pump coupler

(from the fuel pump)

2. Check:

• Fuel pump operation

Faulty/rough movement 

→

 Replace.

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a. Fill the fuel tank.
b. Put the end of the fuel hose “1” into an open 

container.

c. Connect the battery (DC 12 V) to the fuel 

pump terminals as shown.

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

white “1”

• Negative tester probe 

→

black “2”

 

Resistance

4.0–6.0 k

Ω

/blue-black

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

blue “1”

• Negative tester probe 

→

black “2”

B

L

L

W

B

/

W

/

Y

L

1

2

L

Y

B

2

1

ELECTRICAL COMPONENTS

7-90

d. Check the fuel pump operation.

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EAS28360

CHECKING THE EXUP SERVO MOTOR

1. Check:

• EXUP servo motor operation

Out of specification 

→

 Replace.

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a. Disconnect the EXUP cables from the EXUP 

servo motor pulley.

b. Disconnect the EXUP servo motor coupler 

from the wire harness.

c. Connect the battery leads to the EXUP servo 

motor terminals as shown.

d. Check that the EXUP servo motor pulley ro-

tates several times in directions “a” and “b”.

CAUTION:

ECA14390

To prevent damaging the EXUP servo motor, 
perform this test within a few seconds of 
connecting the battery.

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EAS28410

CHECKING THE INTAKE AIR PRESSURE 
SENSOR

The following procedure applies to both of the in-
take air pressure sensors.
1. Check:

• Intake air pressure sensor output voltage

Out of specification 

→

 Replace.

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a. Connect the pocket tester (DC 20 V) to the in-

take air pressure sensor coupler as shown.

b. Turn the main switch to “ON”.
c. Measure the intake air pressure sensor out-

put voltage.

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ET1D71016

CHECKING THE AIR TEMPERATURE 
SENSOR

1. Remove:

• Air temperature sensor

• Positive battery lead 

→

red/blue “2”

• Negative battery lead 

→

black “3”

For counterclockwise rotation “a”
• Positive battery lead 

→

black/green “1”

• Negative battery lead 

→

black/red “2”

For clockwise rotation “b”
• Positive battery lead 

→

black/red “2”

• Negative battery lead 

→

black/green “1”

B

G

/

W

R

/

L

B

3

2

1

L

B

/

L

B

/

R

B

/

G

W

/

R

b

a

2

1

 

Intake air pressure sensor output 
voltage

3.75–4.25 V

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

• Positive tester probe 

→

pink/white “1” or pink/yellow

• Negative tester probe 

→

black/blue “2”

L

B

/

L P

/

W

1

2

ELECTRICAL COMPONENTS

7-91

WARNING

EW1D71004

• Handle the air temperature sensor with 

special care.

• Never subject the air temperature sensor to 

strong shocks. If the air temperature sen-
sor is dropped, replace it.

2. Check:

• Air temperature sensor resistance

Out of specification 

→

 Replace.

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a. Connect the pocket tester (

Ω

 

×

 100) to the air 

temperature sensor terminals as shown.

b. Immerse the air temperature sensor “1” in a 

container filled with water “2”.

NOTE:

Make sure that the air temperature sensor termi-
nals do not get wet.

c. Place a thermometer “3” in the water.
d. Slowly heat the water, then let it cool down to 

the specified temperature.

e. Measure the air temperature sensor resis-

tance.

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Air temperature sensor resis-
tance

290–390 

Ω

 at 80 °C (176 °F)

 

Pocket tester

90890-03112

Analog pocket tester

YU-03112-C

3

1

2