Yamaha XV19SW(C), XV19W(C), XV19MW(C), XV19CTSW(C), XV19CTW(C), XV19CTMW(C). Service Manual - part 25

FUEL INJECTION SYSTEM

7-44

Fault code No.

15

Symptom Throttle position sensor: open or short circuit detected.

Diagnostic code No.

01

Throttle position sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Installed condition of throttle position 
sensor.

• Check for looseness or pinch-

ing.

• Check that the sensor is in-

stalled in the specified position.

Turning the 
main switch to 
“ON”.

2

Connections
• Throttle position sensor coupler
• Main wire harness ECU coupler
• Sub-wire harness 2 coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

3

Open or short circuit in wire harness 
and/or sub lead.

• Repair or replace if there is an 

open or short circuit.

• Between throttle position sen-

sor coupler and ECU coupler
(blue–blue)
(yellow–yellow)
(black–black)

4

Throttle position sensor lead wire 
open circuit output voltage check.

• Check for open circuit and re-

place the throttle position sen-
sor.
(black–yellow)

Open circuit 
item

Output voltage

Ground wire 
open circuit

5 V

Output wire 
open circuit

0 V

Power supply 
wire open cir-
cuit

0 V

5

Defective throttle position sensor.

• Execute the diagnostic mode. 

(Code No.01)

• Replace if defective.

Refer to “CHECKING THE 
THROTTLE POSITION SEN-
SOR” on page 7-89.

FUEL INJECTION SYSTEM

7-45

Fault code No.

17

Symptom EXUP servo motor circuit: open or short circuit detected.

Diagnostic code No.

53

EXUP servo motor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• EXUP servo motor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Turning the 
main switch to 
“ON”.

2

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between servo motor coupler 

and ECU coupler
(blue–blue)
(white/red–white/red)
(black/blue–black/blue)

3

Defective EXUP servo motor (potenti-
ometer circuit).

• Execute the diagnostic mode. 

(Code No.53)

• Replace if defective.

Refer to “CHECKING THE 
EXUP SERVO MOTOR” on 
page 7-90.

Fault code No.

18

Symptom EXUP servo motor is stuck.

Diagnostic code No.

53

EXUP servo motor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• EXUP servo motor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Turning the 
main switch to 
“ON”.
It takes 120 
seconds at the 
maximum be-
fore the origi-
nal state 
returns.

2

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between the EXUP servo motor 

coupler and the ECU coupler.
(black/green–black/green)
(black/red–black/red)

3

Defective EXUP servo motor.

• Execute the diagnostic mode. 

(Code No.53)

• Replace if defective.

Refer to “CHECKING THE 
EXUP SERVO MOTOR” on 
page 7-90.

4

Defective EXUP valve, pulley, cables.

Replace if defective.

FUEL INJECTION SYSTEM

7-46

Fault code No.

19

Symptom A break or disconnection of the blue/black lead of the 

ECU is detected.

Diagnostic code No.

20

Sidestand switch

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Main wire harness ECU coupler

• Execute the diagnostic mode. 

(Code No.20)

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

If the transmis-
sion is in gear, 
retracting the 
sidestand.
If the transmis-
sion is in neu-
tral, 
reconnecting 
the wiring.

2

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between ECU and blue/black 

lead

3

Defective sidestand switch.

• Replace if defective.

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

Fault code No.

22

Symptom Air temperature sensor: open or short circuit detected.

Diagnostic code No.

05

Air temperature sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Installed condition of air temperature 
sensor.

Check for looseness or pinching.

Turning the 
main switch to 
“ON”.

2

Connections
• Air temperature sensor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

3

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between air temperature sen-

sor coupler and ECU coupler
(brown/white–brown/white)
(black/blue–black/blue)

4

Defective air temperature sensor.

• Execute the diagnostic mode. 

(Code No.05)

• Replace if defective.

Refer to “CHECKING THE AIR 
TEMPERATURE SENSOR” on 
page 7-90.

FUEL INJECTION SYSTEM

7-47

Fault code No.

24

Symptom No normal signal is received from the O

2

 sensor.

Diagnostic code No.

—

—

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Installed state of O

2

 sensor.

Check for looseness or pinching.

Starting the en-
gine and oper-
ating it at idle.

2

Connections
• O

2

 sensor coupler

• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

3

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between O

2

 sensor coupler and 

ECU coupler.
(gray/white–gray/white)
(red/blue–red/blue)
(gray/green–gray/green)
(black/blue–black/blue)

4

Check fuel pressure.

• Refer to “THROTTLE BODIES” 

on page 6-6.

5

Defective O

2

 sensor.

• Replace if defective.

FUEL INJECTION SYSTEM

7-48

Fault code No.

25

Symptom Cylinder-#2 intake air pressure sensor: open or short cir-

cuit detected.

Diagnostic code No.

04

Cylinder-#2 intake air pressure sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Cylinder-#2 intake air pressure sen-

sor coupler

• Main wire harness ECU coupler
• Sub-wire harness 3 coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Turning the 
main switch to 
“ON”.

2

Open or short circuit in wire harness 
and/or sub lead.

• Repair or replace if there is an 

open or short circuit.

• Between cylinder-#2 intake air 

pressure sensor coupler and 
ECU coupler
(black/blue–black/blue)
(pink/yellow–pink/yellow)
(blue–blue)

3

Defective cylinder-#2 intake air pres-
sure sensor.

• Execute the diagnostic mode. 

(Code No.04)

• Replace if defective.

Refer to “CHECKING THE IN-
TAKE AIR PRESSURE SEN-
SOR” on page 7-90.

FUEL INJECTION SYSTEM

7-49

Fault code No.

26

Symptom Cylinder-#2 intake air pressure sensor: hose system mal-

function (clogged or detached hose).

Diagnostic code No.

04

Cylinder-#2 intake air pressure sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Cylinder-#2 intake air pressure sensor 
hose

• Check the cylinder-#2 intake air 

pressure sensor hose condition.

• Repair or replace the sensor 

hose.

Starting the en-
gine and oper-
ating it at idle.

2

Cylinder-#2 intake air pressure sensor 
malfunction at intermediate electrical 
potential.

• Check and repair the connec-

tion.

• Replace it if there is a malfunc-

tion.

3

Connections
• Cylinder-#2 intake air pressure sen-

sor coupler

• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

4

Defective cylinder-#2 intake air pres-
sure sensor.

• Execute the diagnostic mode. 

(Code No.04)

• Replace if defective.

Refer to “CHECKING THE IN-
TAKE AIR PRESSURE SEN-
SOR” on page 7-90.

FUEL INJECTION SYSTEM

7-50

Fault code No.

28

Symptom Engine temperature sensor: open or short circuit detect-

ed.

Diagnostic code No.

11

Engine temperature sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Installed state of engine temperature 
sensor.

Check for looseness or pinching.

Turning the 
main switch to 
“ON”.

2

Connections
• Engine temperature sensor coupler
• Main wire harness ECU coupler
• Sub-wire harness 2 coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

3

Open or short circuit in wire harness 
and/or sub lead.

• Repair or replace if there is an 

open or short circuit.

• Between engine temperature 

sensor coupler and ECU cou-
pler
(brown–brown)
(black–black)

4

Defective engine temperature sensor.

• Execute the diagnostic mode. 

(Code No.11)

• Replace if defective.

Refer to “CHECKING THE EN-
GINE TEMPERATURE SEN-
SOR” on page 7-87.

Fault code No.

30

Symptom The vehicle has overturned.

Diagnostic code No.

08

Lean angle sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

The vehicle has overturned.

Raise the vehicle upright.

Turning the 
main switch to 
“ON” (however, 
the engine can-
not be restarted 
unless the main 
switch is first 
turned “OFF”).

2

Installed condition of the lean angle 
sensor.

Check for looseness or pinching.

3

Connections
• Lean angle sensor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

4

Defective lean angle sensor.

• Execute the diagnostic mode. 

(Code No.08)

• Replace if defective.

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

FUEL INJECTION SYSTEM

7-51

Fault code No.

33

Symptom Malfunction detected in the primary wire of the cylinder-#1 

left or right ignition coil.

Diagnostic code No.

30, 32

Cylinder-#1 left or right ignition coil

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Cylinder-#1 left or right ignition coil 

connector (primary coil side)

• Main wire harness ECU coupler

• Check the connector and cou-

pler for any pins that may be 
pulled out.

• Check the locking condition of 

the connector and coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine and oper-
ating it at idle.

2

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between cylinder-#1 left or right 

ignition coil connector and ECU 
coupler/main wire harness.
(black/red–blue/red)
(orange–orange)

3

Defective cylinder-#1 left or right igni-
tion coil.

• Execute the diagnostic mode. 

(Code No.30 or 32)

• Test the primary and secondary 

coils for continuity.

• Replace if defective.

Refer to “CHECKING THE IG-
NITION COILS” on page 7-83.

FUEL INJECTION SYSTEM

7-52

Fault code No.

34

Symptom Malfunction detected in the primary wire of the cylinder-#2 

left or right ignition coil.

Diagnostic code No.

31, 33

Cylinder-#2 left or right ignition coil

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Cylinder-#2 left or right ignition coil 

connector (primary coil side)

• Main wire harness ECU coupler
• Sub-wire harness 3 coupler

• Check the connector and cou-

pler for any pins that may be 
pulled out.

• Check the locking condition of 

the connector and coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine and oper-
ating it at idle.

2

Open or short circuit in wire harness 
and/or sub lead.

• Repair or replace if there is an 

open or short circuit.

• Between cylinder-#2 left or right 

ignition coil connector and ECU 
coupler/main wire harness.
(black/red–blue/red)
(gray/red–gray/red)

3

Defective cylinder-#2 left or right igni-
tion coil.

• Execute the diagnostic mode. 

(Code No.31 or 33)

• Test the primary and secondary 

coils for continuity.

• Replace if defective.

Refer to “CHECKING THE IG-
NITION COILS” on page 7-83.

FUEL INJECTION SYSTEM

7-53

Fault code No.

35

Symptom Malfunction detected in the primary wire of the cylinder-#1 

left or right ignition coil.

Diagnostic code No.

30, 32

Cylinder-#1 left or right ignition coil

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Cylinder-#1 left or right ignition coil 

connector (primary coil side)

• Main wire harness ECU coupler

• Check the connector and cou-

pler for any pins that may be 
pulled out.

• Check the locking condition of 

the connector and coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine and oper-
ating it at idle.

2

Open or short circuit in wire harness.

• Repair or replace if there is an 

open or short circuit.

• Between cylinder-#1 left or right 

ignition coil connector and ECU 
coupler/main wire harness.
(black/red–blue/red)
(orange–orange)

3

Defective cylinder-#1 left or right igni-
tion coil.

• Execute the diagnostic mode. 

(Code No.30 or 32)

• Test the primary and secondary 

coils for continuity.

• Replace if defective.

Refer to “CHECKING THE IG-
NITION COILS” on page 7-83.

FUEL INJECTION SYSTEM

7-54

Fault code No.

36

Symptom Malfunction detected in the primary wire of the cylinder-#2 

left or right ignition coil.

Diagnostic code No.

31, 33

Cylinder-#2 left or right ignition coil

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Cylinder-#2 left or right ignition coil 

connector (primary coil side)

• Main wire harness ECU coupler
• Sub-wire harness 3 coupler

• Check the connector and cou-

pler for any pins that may be 
pulled out.

• Check the locking condition of 

the connector and coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine and oper-
ating it at idle.

2

Open or short circuit in wire harness 
and/or sub lead.

• Repair or replace if there is an 

open or short circuit.

• Between cylinder-#2 left or right 

ignition coil connector and ECU 
coupler/main wire harness.
(black/red–blue/red)
(gray/red–gray/red)

3

Defective cylinder-#2 left or right igni-
tion coil.

• Execute the diagnostic mode. 

(Code No.31 or 33)

• Test the primary and secondary 

coils for continuity.

• Replace if defective.

Refer to “CHECKING THE IG-
NITION COILS” on page 7-83.

FUEL INJECTION SYSTEM

7-55

Fault code No.

37

Symptom Engine speed is high when the engine is idling.

Diagnostic code No.

54

ISC valve

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

ECU fuse is blown.

• Check the ECU fuse.

Refer to “CHECKING THE 
FUSES” on page 7-75.

ISC valve re-
turns to its orig-
inal position by 
turning the 
main switch to 
“ON” and back 
to “OFF”.
Reinstated if 
the engine idle 
speed is within 
specification af-
ter starting the 
engine.

2

Throttle valve does not fully close.

• Check the throttle bodies.

Refer to “THROTTLE BODIES” 
on page 6-6.

• Check the throttle cables.

Refer to “ADJUSTING THE 
THROTTLE CABLE FREE 
PLAY” on page 3-8.

3

ISC valve is stuck fully open due to 
disconnected ISC unit hose or cou-
pler. (High engine idle speed is de-
tected with the ISC valve stuck fully 
open even though signals for the valve 
to close are continuously being trans-
mitted by the ECU.)

• Check that the ISC unit hose is 

not disconnected.

• Check that the ISC unit coupler 

is not disconnected.

• The ISC valve is stuck fully 

open if it does not operate when 
the main switch is turned “OFF”.
(Touch the ISC unit with your 
hand and check if it is vibrating 
to confirm if the ISC valve is op-
erating.)

4

ISC valve is not moving correctly.

• Execute the diagnostic mode. 

(Code No.54)

• After the ISC valve is fully 

closed, it opens to the standby 
opening position when the en-
gine is started. This operation 
takes approximately 12 sec-
onds. Start the engine. If the er-
ror recurs, replace the throttle 
body assembly.

FUEL INJECTION SYSTEM

7-56

Fault code No.

41

Symptom Lean angle sensor: open or short circuit detected.

Diagnostic code No.

08

Lean angle sensor

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Lean angle sensor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Turning the 
main switch to 
“ON”.

2

Open or short circuit in lead wire.

• Repair or replace if there is an 

open or short circuit.

• Between lean angle sensor 

coupler and ECU coupler.
(blue–blue)
(yellow/green–yellow/green)
(black/blue–black/blue)

3

Defective lean angle sensor.

• Execute the diagnostic mode. 

(Code No.08)

• Replace if defective.

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

FUEL INJECTION SYSTEM

7-57

Fault code No.

42

Symptom A. No normal signals are received from the speed sensor.

B. Open circuit is detected in the neutral switch.

Diagnostic code No.

A

07

Speed sensor

B

21

Neutral switch

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

A-1

Connections
• Speed sensor coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine, and acti-
vating the 
vehicle speed 
sensor by oper-
ating the vehi-
cle at 20 to 30 
km/h.

A-2

Open or short circuit in speed sensor 
lead.

• Repair or replace if there is an 

open or short circuit.

• Between speed sensor coupler 

and ECU coupler.
(blue–blue)
(white/yellow–white/yellow)
(black/blue–black/blue)

A-3

Gear for detecting vehicle speed has 
broken.

• Replace if defective.

Refer to “TRANSMISSION” on 
page 5-107.

A-4

Defective speed sensor.

• Execute the diagnostic mode. 

(Code No.07)

• Replace if defective.

Refer to “CHECKING THE 
SPEED SENSOR” on page 
7-88.

FUEL INJECTION SYSTEM

7-58

B-1

Connections
• Neutral switch coupler
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine, and acti-
vating the 
vehicle speed 
sensor by oper-
ating the vehi-
cle at 20 to 30 
km/h.

B-2

Open circuit in neutral switch lead.

• Repair or replace if there is an 

open circuit.

• Between neutral switch coupler 

and relay unit coupler (fuel 
pump relay).
(sky blue–sky blue)

• Between relay unit coupler and 

main switch.
(blue/yellow–blue/yellow)

• Between main switch and ECU 

coupler.
(blue/black–blue/black)

B-3

Faulty shift drum (neutral detection ar-
ea).

• Replace if defective.

Refer to “TRANSMISSION” on 
page 5-107.

B-4

Defective neutral switch.

• Execute the diagnostic mode. 

(Code No.21)

• Replace if defective.

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

Fault code No.

42

Symptom A. No normal signals are received from the speed sensor.

B. Open circuit is detected in the neutral switch.

Diagnostic code No.

A

07

Speed sensor

B

21

Neutral switch

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

FUEL INJECTION SYSTEM

7-59

Fault code No.

43

Symptom The ECU is unable to monitor the battery voltage (an open 

or short circuit in the line to the ECU).

Diagnostic code No.

09

Fuel system voltage

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Connections
• Relay unit coupler (fuel pump relay)
• Main wire harness ECU coupler

• Check the coupler for any pins 

that may be pulled out.

• Check the locking condition of 

the coupler.

• If there is a malfunction, repair it 

and connect the coupler se-
curely.

Starting the en-
gine and oper-
ating it at idle.

2

Open or short circuit in the wire har-
ness.

• Repair or replace if there is an 

open or short circuit.

• Between relay unit coupler (fuel 

pump relay) and ECU coupler.
(blue/red–blue/red)
(red/blue–red/blue)

• Between relay unit coupler (fuel 

pump relay) and battery termi-
nal.
(red–red)

• Between relay unit coupler (fuel 

pump relay) and diode 2 cou-
pler.
(red/white–red/white)

• Between diode 2 coupler and 

engine stop switch coupler.
(black/red–black/red)

3

Malfunction or open circuit in relay 
unit (fuel pump relay).

• Execute the diagnostic mode. 

(Code No. 09)

• Replace if defective.
• If there is no malfunction with 

the relay unit (fuel pump relay), 
replace the ECU.

Fault code No.

44

Symptom Error is detected while reading or writing on EEPROM (CO 

adjustment value).

Diagnostic code No.

60

EEPROM improper cylinder indication

Order Item/components and probable 

cause

Check or maintenance job

Reinstatement 
method

1

Malfunction in ECU.

• Execute the diagnostic mode. 

(Code No. 60)
1. Check the faulty cylinder. (If 

multiple cylinders are defec-
tive, the number of the faulty 
cylinders appears alternate-
ly at 2-second intervals.)

• Replace ECU if defective.

Turning the 
main switch to 
“ON”.