Yamaha XV19SW(C), XV19W(C), XV19MW(C), XV19CTSW(C), XV19CTW(C), XV19CTMW(C). Service Manual - part 22

ISC (IDLE SPEED CONTROL) UNIT

6-14

ET1D71009

ISC (IDLE SPEED CONTROL) UNIT

Removing the ISC (idle speed control) unit

Order

Job/Parts to remove

Q’ty

Remarks

Front cylinder head

Refer to “CYLINDER HEADS” on page 5-33.

1

Sub-wire harness 4

1

2

Sub-wire harness 3

1

3

Cylinder-#2 ISC (idle speed control) unit outlet 
hose

2

4

Cylinder-#1 ISC (idle speed control) unit outlet 
hose

2

5

ISC (idle speed control) unit inlet hose

1

6

Cylinder-#2 left ignition coil

1

7

Cylinder-#2 right ignition coil

1

8

ISC (idle speed control) unit

1

9

ISC (idle speed control) unit bracket

1

For installation, reverse the removal proce-
dure.

6

7

9

3

3

5

4

4

1

8

2

T

 

R

7 Nm (0.7 m

 

•

 kg, 5.1 ft 

•

 Ib)

T

 

R

7 Nm (0.7 m

 

•

 kg, 5.1 ft 

•

 Ib)

 

R

7 Nm (0.7 m

 

•

 kg, 5.1 ft 

•

 Ib)

(4)

T

 

R

7 Nm (0.7 m

 

•

 kg, 5.1 ft 

•

 Ib)

ISC (IDLE SPEED CONTROL) UNIT

6-15

ET1D71010

CHECKING THE ISC (IDLE SPEED 
CONTROL) SYSTEM

1. Check:

• Hoses

Loose connections 

→

 Connect properly.

Cracks/damage 

→

 Replace.

7

ELECTRICAL SYSTEM

IGNITION SYSTEM

......................................................................................... 7-1

CIRCUIT DIAGRAM .................................................................................. 7-1
ENGINE STOPPING DUE TO SIDESTAND OPERATION....................... 7-3
TROUBLESHOOTING .............................................................................. 7-4

ELECTRIC STARTING SYSTEM

.................................................................... 7-7

CIRCUIT DIAGRAM .................................................................................. 7-7
STARTING CIRCUIT CUT-OFF SYSTEM OPERATION.......................... 7-9
TROUBLESHOOTING ............................................................................ 7-11

CHARGING SYSTEM

................................................................................... 7-13

CIRCUIT DIAGRAM ................................................................................ 7-13
TROUBLESHOOTING ............................................................................ 7-15

LIGHTING SYSTEM

...................................................................................... 7-17

CIRCUIT DIAGRAM ................................................................................ 7-17
TROUBLESHOOTING ............................................................................ 7-19

SIGNALING SYSTEM

................................................................................... 7-21

CIRCUIT DIAGRAM ................................................................................ 7-21
TROUBLESHOOTING ............................................................................ 7-23

FUEL INJECTION SYSTEM

......................................................................... 7-27

CIRCUIT DIAGRAM ................................................................................ 7-27
ECU SELF-DIAGNOSTIC FUNCTION.................................................... 7-29
SELF-DIAGNOSTIC FUNCTION TABLE................................................ 7-30
TROUBLESHOOTING METHOD............................................................ 7-32
DIAGNOSTIC MODE .............................................................................. 7-33
TROUBLESHOOTING DETAILS ............................................................ 7-40

FUEL PUMP SYSTEM

.................................................................................. 7-63

CIRCUIT DIAGRAM ................................................................................ 7-63
TROUBLESHOOTING ............................................................................ 7-65

ELECTRICAL COMPONENTS

..................................................................... 7-67

CHECKING THE SWITCHES ................................................................. 7-71
CHECKING THE BULBS AND BULB SOCKETS ................................... 7-74
CHECKING THE FUSES ........................................................................ 7-75
CHECKING AND CHARGING THE BATTERY....................................... 7-76
CHECKING THE RELAYS ...................................................................... 7-79
CHECKING THE TURN SIGNAL RELAY ............................................... 7-80
CHECKING THE DIODES ...................................................................... 7-81
CHECKING THE IGNITION SPARK GAP .............................................. 7-82
CHECKING THE SPARK PLUG CAPS .................................................. 7-83
CHECKING THE IGNITION COILS ........................................................ 7-83
CHECKING THE CRANKSHAFT POSITION SENSOR ......................... 7-84
CHECKING THE LEAN ANGLE SENSOR ............................................. 7-84
CHECKING THE STARTER MOTOR OPERATION............................... 7-85
CHECKING THE STATOR COIL ............................................................ 7-85
CHECKING THE RECTIFIER/REGULATOR.......................................... 7-85
CHECKING THE HORNS ....................................................................... 7-86
CHECKING THE ENGINE TEMPERATURE SENSOR .......................... 7-87
CHECKING THE FUEL SENDER (FUEL TANK).................................... 7-87
CHECKING THE FUEL SENDER (FUEL PUMP) ................................... 7-88
CHECKING THE FUEL LEVEL WARNING LIGHT................................. 7-88
CHECKING THE SPEED SENSOR........................................................ 7-88
CHECKING THE THROTTLE POSITION SENSOR............................... 7-89
CHECKING THE FUEL PUMP................................................................ 7-89
CHECKING THE EXUP SERVO MOTOR .............................................. 7-90
CHECKING THE INTAKE AIR PRESSURE SENSOR ........................... 7-90
CHECKING THE AIR TEMPERATURE SENSOR.................................. 7-90

IGNITION SYSTEM

7-1

EAS27090

IGNITION SYSTEM

EAS27110

CIRCUIT DIAGRAM

W

W

W

R

R

/

G

B

(GRA

Y)

ON

OFF

R

Br

R

B

/

L

R

L

/

Y

Br

L

L

/

B

R

R

R

R

R

B

B

B

R

R

R

B

R

/

Y

L

B

R

WR

/

W

R

/

Y

R

/

Y

R

/

W

R

/

W

R

/

L

R

L

Y

L

R

R

Y

L

W

Sb

W

Sb

L

L

B

/

Y

R

R

/

L

L

GS

b

/

W

L

L

W

R

/

W

L

R

/

Y

L

RB

/

Y

L

/

YS

b

L

G

B

(BLUE)

L

/

G

B

(BLUE)

B

B

L

/

G

R

/

W

Sb

B

Sb

B

B

B

Y

L

Y

Y

E

B

B

E

L

L

E

Y

(BLA

CK)

L

B

B

/

L

Gy

Gy

B

Gy

B

/

L

B

/

L

L

P

/

Y

B

/

L

L

P

W

P

W

(BLA

CK)

B

L

L

P

Y

(BLA

CK)

B

/

L

L

W

L

B

L

W

Y

B

/

L

L

B

L

W

/

Y

G

W

B

/

L

Br

/

W

(BLA

CK)

(BLA

CK)

B

B

Br

Br

Br

B

B

B

Br

W

B

/

L

B

G

/

W

R

/

L

B

R

/

L

G

W

B

B

B

/

L

L

Y

/

G

B

/

L

Y

G

L

Br

Br

/

L

Br

/

L

R

Br

L

R

B

Br

/

L

R

/

W

R

/

Y

B

Br

Br

B

R

/

B

Br

L

R

Y

Br

BB

B
Y

Y

/

B

R

/

Y

G

/

L

Br

Y

B

G

/

L

R

Y

Br

(GRAY)

(GRAY)

(GRAY)

(GRAY)

(GRAY)

B

B

G

Y

G

B

(BLUE)

(BLUE)

YG

G

L

(GRAY)

(BLACK)

BB

R

/

W

B

/

R

G

LL

/

B

(BLACK)

B

L

/

B

B
B

L

Y

B

B

/

R

Y

/

B

G

Gy

R

Gy

R

O

O

Gy

W

B

/

G

B

B

Gy

Y

G

Br

L

B

Y

Y

L

Gy

L

R

L

B

R

/

L

R

/

W

Y

W

Y

W

R

W

/

G

R

/

B

R

/

B

R

/

G

Br

Gy

G

P

/

W

P

L

P

/

Y

Br

W

B

/

Br

B

/

Br

B

/

L

L

W

L

(BLA

CK)

B

B

(L)

N

(R)

(BLACK)

(BLACK)

B

B

Dg

L

Dg
L

B

L

Dg

PUSH

B

Y

B

Y

(BLA

CK)

(BLA

CK)

G
B

B

B

A

Y

Y

A

Ch

Ch

A

Dg

Dg

A

B

B

W

P

Br

BG

R

B

R

B

R

G

P

L

W

G

/

P

/

L

W

G

Br

/

L

R

/

G

P

/

L

W

G

Br

L

Gy

/

R

Gy

/

R

Gy

R

Gy

R

R

/

G

P

L

W

/

G

B

/

L

R

G

P

/

L

W

/

G

B

/

L

R

/

G

R

/

B

R

/

B

R

/

B

R

/

B

R

/

B

R

/

B

C

C

D

Y

/

B

Gy

W

W

R

B

/

G

B

/

R

W

/

R

(BLA

CK)

L

W

R

B

G

R

B

L

L

B

/

G

B

/

R

B

/

L

W

G

(GRA

Y)

W

Gy

(D

ARK GRA

Y)

Gy

G

G

Gy

G

Gy

Gy

W

(BLACK)

R

L

B

L

Gy

/

G

Gy

/

W

BB

WL

R

L

Gy

W

Gy

/

G

B

L

Sb

/

W

Dg

Ch

Y

G

/

B

G

G

/

Y

Y

/

L

R

G

G

W

R

W

L

L

Ch

Sb

W

Y

R

W

Dg

L

Sb

Y

Ch

R

/

W

Dg

(BLACK)

G

/

W

B

Y

L

G

R

G

(BLACK)

(BLACK)

(BLACK)

G

/

W

B

Y

/

L

G

R

/

G

G

/

Y

G

/

Y

G

/

B

G

/

B

B

(GRAY)

(GRAY)

B

B

Ch

L

Ch
L

B

L

Ch

Gy

R

Gy

R

Gy

/

R

Gy

/

R

O

O

B

R

B

R

B

R

B

R

B

/

R

B

/

R

O

O

Y

L

Gy

/

G

D
D

R

/

W

L

Y

Gy

P

/

Y

B

/

Y

Y

/

G

L

/

R

R

L

R

/

B

R

/

B

P

/

W

Br

B

/

W

L

/

W

W

Y

B

L

L

/

B

B

B

B

/

Br

B

/

Br

R

/

W

B

/

R

R

/

W

B

R

Br

Br

/

W

B

Y

/

R

W

/

Y

Br

/

W

Y

/

R

P

G

Y

G

L

B

Y

L

/

Y

Y

Dg

G

/

B

B

Ch

G

Y

G

B

B

Ch

Dg

B

B

B

L

G

/

L

L

/

W

B

/

R

R

/

W

Y

Br

W

/

B

B

L

B

L

B

P

Br

(BLA

CK)

(BLA

CK)

B

R

W

W

B

W

W

B

G

B

G

B

L

L

A

(BLACK)

(BLACK)

R

Y

R

L

(GRAY)

L

/

BL

/

Y

(GRAY)

/

B

/

Y

W

W
W

Y

/

R

Br

W

B

W

Y

Br

Y

G

G

/

L

R

W

B

/

R

L

B

G

/

L

Br

Y

L

/

Y

B

/

Y

G

/

B

G

/

Y

Dg

h

rW

B

P

R

Dg

Ch

B

/

W

B

P

Y

R

W

B

/

W

W

B

L

W

B

L

Ch

Y

Dg

L

Ch

B

Y

Dg

A

W

RE HARNESS

W

RE HARNESS

W

RE HARNESS

W

RE HARNESS

 SUB

W

RE

HARNESS2

Y

L

B

Y

L

B

E

W

RE HARNESS

 SUB

W

RE

HARNESS1

 SUB

W

RE

HARNESS2

 SUB

W

RE

HARNESS4

 SUB

W

RE

HARNESS3

(BLACK)

(BLACK)

B

C

D

Gy

R

y

R

B

R

y

R

Gy

R

B

/

R

G

B

W

Gy

W

Br

G

W

Gy

B

W

Br

(BLACK)

R

/

B

P

L

R

/

B

W

G

B

/

L

R

G

(BLACK)

R

/

B

R

/

B

W

G

P

/

L

Br

L

R

/

G

IGNITION SYSTEM

7-2

3. Main switch
4. Main fuse
6. Battery
11.Relay unit
14.Neutral switch
16.Sidestand switch
19.Crankshaft position sensor
23.Lean angle sensor
27.ECU (electronic control unit)
28.Cylinder-#1 left ignition coil
29.Cylinder-#1 right ignition coil
30.Cylinder-#2 left ignition coil
31.Cylinder-#2 right ignition coil
32.Spark plug
68.Engine stop switch
77.Ignition fuse
81.ECU fuse

IGNITION SYSTEM

7-3

ET1D71043

ENGINE STOPPING DUE TO SIDESTAND OPERATION

When the engine is running and the transmission is in gear, the engine will stop if the sidestand is 
moved down. This is because the electric current from the ignition coils does not flow to the ECU when 
both the neutral switch and sidestand switch are set to “OFF”, thereby preventing the spark plugs from 
producing a spark. However, the engine continues to run under the following conditions:
• The transmission is in gear (the neutral switch circuit is open) and the sidestand is up (the sidestand 

switch circuit is closed).

• The transmission is in neutral (the neutral switch circuit is closed) and the sidestand is down (the sid-

estand switch circuit is open).

1

4

5

10

11

9

7

2

6

3

8

1. Battery
2. Main fuse
3. Main switch
4. Ignition fuse
5. Engine stop switch
6. Ignition coil
7. Spark plug
8. ECU (electronic control unit)
9. Sidestand switch
10. Relay unit (diode)
11. Neutral switch

IGNITION SYSTEM

7-4

EAS27140

TROUBLESHOOTING

The ignition system fails to operate (no spark or intermittent spark).

NOTE:

• Before troubleshooting, remove the following part(s):
1. Rider seat
2. Tool kit tray
3. Rider seat bracket assembly
4. Fuel tank
5. Air filter case
6. Headlight assembly
7. Exhaust pipes
8. Front cylinder

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 OK

 →

NG

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

1. Check the fuses.

(Main, ignition and ECU)
Refer to “CHECKING THE FUS-
ES” on page 7-75.

Replace the fuse(s).

2. Check the battery.

Refer to “CHECKING AND 
CHARGING THE BATTERY” on 
page 7-76.

• Clean the battery terminals.
• Recharge or replace the battery.

3. Check the spark plugs.

Refer to “CHECKING THE SPARK 
PLUGS” on page 3-9.

Re-gap or replace the spark plug(s).

4. Check the ignition spark gap.

Refer to “CHECKING THE IGNI-
TION SPARK GAP” on page 7-82.

Ignition system is OK.

5. Check the spark plug caps.

Refer to “CHECKING THE SPARK 
PLUG CAPS” on page 7-83.

Replace the spark plug cap(s).

6. Check the ignition coils.

Refer to “CHECKING THE IGNI-
TION COILS” on page 7-83.

Replace the ignition coil(s).

7. Check the crankshaft position sen-

sor.
Refer to “CHECKING THE CRANK-
SHAFT POSITION SENSOR” on 
page 7-84.

Replace the crankshaft position sensor.

IGNITION SYSTEM

7-5

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

8. Check the main switch.

Refer to “CHECKING THE 
SWITCHES” on page 7-71.

Replace the main switch.

9. Check the engine stop switch.

Refer to “CHECKING THE 
SWITCHES” on page 7-71.

The engine stop switch is faulty. Replace 
the right handlebar switch.

10.Check the neutral switch.

Refer to “CHECKING THE 
SWITCHES” on page 7-71.

Replace the neutral switch.

11.Check the sidestand switch.

Refer to “CHECKING THE 
SWITCHES” on page 7-71.

Replace the sidestand switch.

12.Check the relay unit (diode).

Refer to “CHECKING THE DI-
ODES” on page 7-81.

Replace the relay unit.

13.Check the lean angle sensor.

Refer to “CHECKING THE LEAN 
ANGLE SENSOR” on page 7-84.

Replace the lean angle sensor.

14.Check the entire ignition system 

wiring.
Refer to “CIRCUIT DIAGRAM” on 
page 7-1.

Properly connect or repair the ignition sys-
tem wiring.

Replace the ECU.

IGNITION SYSTEM

7-6

ELECTRIC STARTING SYSTEM

7-7

EAS27160

ELECTRIC STARTING SYSTEM

EAS27170

CIRCUIT DIAGRAM

W

W

W

R

R

/

G

B

(GRA

Y)

ON

OFF

R

Br

R

B

/

L

R

L

/

Y

Br

L

L

/

B

R

R

R

R

R

B

B

B

R

R

R

B

R

/

Y

L

B

R

WR

/

W

R

/

Y

R

/

Y

R

/

W

R

/

W

R

L

R

L

/

Y

L

R

R

Y

L

W

Sb

W

Sb

L

L

B

/

Y

R

R

/

L

L

GS

b

/

W

L

L

W

R

/

W

L

R

/

Y

L

RB

/

Y

L

/

YS

b

L

G

B

(BLUE)

L

/

G

B

(BLUE)

B

B

L

/

G

R

/

W

b

B

Sb

B

B

B

Y

L

Y

Y

E

B

B

E

L

L

E

Y

(BLA

CK)

L

B

B

/

L

Gy

Gy

B

Gy

B

/

L

B

/

L

L

P

/

Y

B

/

L

L

P

W

W

(BLA

CK)

B

L

L

P

Y

(BLA

CK)

B

L

L

W

L

B

L

W

Y

B

L

L

B

L

W

Y

G

W

B

/

L

Br

/

W

(BLA

CK)

(BLA

CK)

B

B

Br

Br

Br

B

B

B

Br

W

B

/

L

B

G

/

W

R

/

L

B

R

/

L

G

W

B

B

B

L

L

Y

/

G

B

/

L

Y

G

L

Br

Br

/

L

Br

/

L

R

Br

L

R

B

Br

/

L

R

/

W

R

/

Y

B

Br

Br

B

R

L

B

Br

L

R

Y

Br

BB

Br
Y

Y

/

B

R

/

Y

G

/

L

Br

Y

B

G

/

L

R

Y

Br

(GRAY)

(GRAY)

(GRAY)

(GRAY)

(GRAY)

B

B

G

Y

G

B

(BLUE)

(BLUE)

YG

G

L

(GRAY)

(BLACK)

BB

R

/

W

B

/

R

G

LL

/

B

(BLACK)

B

L

/

B

B
B

L

Y

B

B

/

R

Y

/

B

G

G

/

R

G

/

R

O

O

Gy

W

B

/

G

B

B

Gy

Y

G

Br

L

B

Y

Y

L

Gy

L

R

L

B

R

/

L

R

/

W

Y

W

Y

W

R

W

/

G

R

/

B

R

/

B

R

/

G

Br

Gy

G

P

/

W

P

/

L

P

/

Y

Br

W

B

/

Br

B

/

Br

B

/

L

L

W

L

(BLA

CK)

B

B

(L)

N

(R)

(BLACK)

(BLACK)

B

B

Dg

L

Dg
L

B

L

Dg

PUSH

B

Y

B

Y

(BLA

CK)

(BLA

CK)

G
B

B

B

A

Y

Y

A

Ch

Ch

A

Dg

Dg

A

B

B

W

P

Br

BG

R

B

R

B

R

/

G

P

L

W

G

Br

/

P

/

L

W

G

Br

/

L

R

/

G

P

/

L

W

/

G

Br

L

Gy

/

R

Gy

/

R

Gy

R

Gy

R

R

/

G

P

L

W

/

G

Br

/

L

R

G

P

/

L

W

/

G

B

/

L

R

/

G

R

/

B

R

/

B

R

/

B

R

/

B

R

/

B

R

/

B

C

C

Y

/

B

Gy

W

W

R

B

/

G

B

/

R

W

/

R

(BLA

CK)

L

W

R

B

G

R

L

L

B

/

G

B

/

R

B

/

L

W

G

(GRA

Y)

W

Gy

(D

ARK GRA

Y)

Gy

G

G

Gy

G

Gy

Gy

W

(BLACK)

R

L

B

L

Gy

/

G

Gy

/

W

BB

WL

R

L

Gy

W

Gy

/

G

B

L

Sb

/

W

Dg

Ch

Y

G

/

B

G

G

/

Y

Y

/

L

R

G

G

W

R

W

L

L

Ch

Sb

W

Y

R

W

Dg

L

Sb

Y

Ch

R

/

W

Dg

(BLACK)

G

/

W

B

Y

L

G

R

/

G

(BLACK)

(BLACK)

(BLACK)

G

/

W

B

Y

/

L

G

R

G

G

/

Y

G

/

Y

G

/

B

G

/

B

B

(GRAY)

(GRAY)

B

B

Ch

L

Ch
L

B

L

Ch

Gy

R

Gy

R

Gy

/

R

Gy

/

R

O

O

B

R

B

R

B

R

B

R

B

/

R

B

/

R

O

O

Y

/

L

Gy

/

G

D
D

R

/

W

L

Y

Gy

P

/

Y

B

/

Y

Y

/

G

L

/

R

R

L

R

/

B

R

/

B

P

/

W

Br

B

/

W

L

/

W

W

Y

B

/

L

L

/

B

B

B

B

/

Br

B

/

Br

R

/

W

B

/

R

R

/

W

B

R

Br

Br

/

W

B

Y

/

R

W

/

Y

Br

/

W

Y

/

R

P

G

/

Y

G

L

B

Y

L

/

Y

Y

Dg

G

/

B

B

Ch

G

Y

G

B

B

Ch

Dg

B

B

B

L

G

/

L

L

/

W

B

/

R

R

/

W

Y

Br

W

/

B

B

L

B

L

B

P

Br

(BLA

CK)

(BLA

CK)

B

R

W

W

B

W

W

B

G

B

G

B

L

L

A

(BLACK)

(BLACK)

R

Y

R

L

(GRAY)

L

/

BL

/

Y

(GRAY)

/

B

L

/

Y

W

W
W

Y

/

R

B

/

W

B

W

Y

Br

Y

G

G

/

L

R

W

B

R

L

B

G

/

L

Br

Y

L

Y

B

/

Y

G

/

B

G

/

Y

Dg

h

Br

W

B

P

Y

R

Dg

Ch

B

/

W

B

P

R

W

B

/

W

W

B

L

W

B

L

Ch

Y

Dg

L

Ch

B

Y

Dg

A

W

RE HARNESS

W

RE HARNESS

W

RE HARNESS

W

RE HARNESS

 SUB

W

RE

HARNESS2

Y

L

B

Y

L

B

W

RE HARNESS

 SUB

W

RE

HARNESS1

 SUB

W

RE

HARNESS2

 SUB

W

RE

HARNESS4

 SUB

W

RE

HARNESS3

(BLACK)

(BLACK)

C

D

Gy

R

y

R

B

/

R

y

R

Gy

R

B

/

R

G

B

W

Gy

W

Br

G

W

Gy

B

W

Br

(BLACK)

R

/

B

P

L

R

/

B

W

G

Br

/

L

R

G

(BLACK)

R

/

B

R

/

B

W

G

P

/

L

Br

L

R

/

G

ELECTRIC STARTING SYSTEM

7-8

3. Main switch
4. Main fuse
6. Battery
8. Starter relay
9. Starter motor
10.Diode 1
11.Relay unit
12.Starting circuit cut-off relay
14.Neutral switch
15.Diode 2
16.Sidestand switch
27.ECU (electronic control unit)
54.Clutch switch
68.Engine stop switch
69.Start switch
77.Ignition fuse
81.ECU fuse

ELECTRIC STARTING SYSTEM

7-9

EAS27180

STARTING CIRCUIT CUT-OFF SYSTEM OPERATION

If the engine stop switch is set to “

” and the main switch is turned “ON” (both switch circuits are 

closed), the starter motor can only operate if at least one of the following conditions is met:
• The transmission is in neutral (the neutral switch circuit is closed).
• The clutch lever is pulled to the handlebar (the clutch switch circuit is closed) and the sidestand is up 

(the sidestand switch circuit is closed).

The starting circuit cut-off relay prevents the starter motor from operating when neither of these condi-
tions has been met. In this instance, the starting circuit cut-off relay stays 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 pushing the start switch “

”.

14

1

15

13

4

5

8

8

a

b

10

8

11

9

7

2

3

16

12

6

17

ELECTRIC STARTING SYSTEM

7-10

a. WHEN THE TRANSMISSION IS IN 

NEUTRAL

b. WHEN THE SIDESTAND IS UP AND THE 

CLUTCH LEVER IS PULLED TO THE 
HANDLEBAR

1. Battery
2. Main fuse
3. Main switch
4. Ignition fuse
5. Engine stop switch
6. Diode 2
7. Relay unit (starting circuit cut-off relay)
8. Relay unit (diode)
9. Clutch switch
10. Sidestand switch
11. Neutral switch
12. Start switch
13. Starter relay
14. Starter motor
15. ECU fuse
16. ECU (electronic control unit)
17. Diode 1

ELECTRIC STARTING SYSTEM

7-11

EAS27190

TROUBLESHOOTING

The starter motor fails to turn.

NOTE:

• Before troubleshooting, remove the following part(s):
1. Rider seat
2. Tool kit tray
3. Headlight assembly

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 OK

 →

NG

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

 

 NG

 →

OK

 ↓

1. Check the fuses.

(Main, ignition and ECU)
Refer to “CHECKING THE FUS-
ES” on page 7-75.

Replace the fuse(s).

2. Check the battery.

Refer to “CHECKING AND 
CHARGING THE BATTERY” on 
page 7-76.

• Clean the battery terminals.
• Recharge or replace the battery.

3. Check the starter motor operation.

Refer to “CHECKING THE START-
ER MOTOR OPERATION” on page 
7-85.

Starter motor is OK. Perform the electric 
starting system troubleshooting, starting 
with step 5.

4. Check the starter motor.

Refer to “CHECKING THE START-
ER MOTOR” on page 5-79.

Repair or replace the starter motor.

5. Check the relay unit (starting circuit 

cut-off relay).
Refer to “CHECKING THE RE-
LAYS” on page 7-79.

Replace the relay unit.

6. Check the relay unit (diode).

Refer to “CHECKING THE DI-
ODES” on page 7-81.

Replace the relay unit.

7. Check the diode 1.

Refer to “CHECKING THE DI-
ODES” on page 7-81.

Replace the diode 1.

8. Check the diode 2.

Refer to “CHECKING THE DI-
ODES” on page 7-81.

Replace the diode 2.