Yamaha Mt 01 T 2005 Manual

							FUEL INJECTION SYSTEM
7-56
Fault code No. 38 Symptom Decompression solenoid: open or short circuit detected.
Diagnostic code No. 55 Decompression solenoid
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Installed state of decompression 
solenoid.Check for looseness or pinching. Turning the 
main switch to 
“ON”.
2 Connections
Decompression solenoid coupler
Main wire harness ECU couplerCheck 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 
securely.
3 Open or short circuit in wire harness.Repair or replace if there is an 
open or short circuit.
Between decompression 
solenoid coupler and ECU 
coupler
(light green–light green)
Between decompression 
solenoid coupler and auto 
decompression fuse
(gray/red–gray/red)
4 Defective decompression solenoid.Execute the diagnostic mode. 
(Code No.55)
Replace if defective.
Refer to “CHECKING THE 
DECOMPRESSION 
SOLENOID” on page 7-105. 
						

							FUEL INJECTION SYSTEM
7-57
Fault code No. 41 Symptom Lean angle cut-off switch: open or short circuit detected.
Diagnostic code No. 08 Lean angle cut-off switch
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Lean angle cut-off switch coupler
Main wire harness ECU couplerCheck 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 
securely.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 cut-off 
switch coupler and ECU 
coupler.
(blue–blue)
(yellow/green–yellow/green)
(black/blue–black/blue)
3 Defective lean angle cut-off switch.Execute the diagnostic mode. 
(Code No.08)
Replace if defective.
Refer to “CHECKING THE 
LEAN ANGLE CUT-OFF 
SWITCH” on page 7-100. 
						

							FUEL INJECTION SYSTEM
7-58
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 
causeCheck or maintenance job Reinstatement 
method
A-1 Connections
Speed sensor coupler
Main wire harness ECU couplerCheck 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 
securely.Starting the 
engine, and 
activating the 
vehicle speed 
sensor by 
operating the 
vehicle 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 5-92.
A-4 Defective speed sensor.Execute the diagnostic mode. 
(Code No.07)
Replace if defective.
Refer to “CHECKING THE 
SPEED SENSOR” on page 
7-103. 
						

							FUEL INJECTION SYSTEM
7-59
B-1 Connections
Neutral switch coupler
Main wire harness ECU couplerCheck 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 
securely.Starting the 
engine, and 
activating the 
vehicle speed 
sensor by 
operating the 
vehicle 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 fuel pump relay coupler.
(sky blue–sky blue)
Between fuel pump relay 
coupler and ECU coupler.
(blue/yellow–blue/yellow)
B-3 Faulty shift drum (neutral detection 
area).Replace if defective.
Refer to “TRANSMISSION” on 
page 5-92.
B-4 Defective neutral switch.Execute the diagnostic mode. 
(Code No.21)
Replace if defective.
Refer to “CHECKING THE 
SWITCHES” on page 7-89. 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 
causeCheck or maintenance job Reinstatement 
method 
						

							FUEL INJECTION SYSTEM
7-60
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 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Relay unit coupler (fuel pump relay)
Main wire harness ECU couplerCheck 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 
securely.Starting the 
engine and 
operating it at 
idle.
2 Open or short circuit in the wire 
harness.Repair or replace if there is an 
open or short circuit.
Between fuel pump relay 
coupler and ECU coupler.
(blue/red–blue/red)
(red/blue–red/blue)
Between fuel pump relay 
coupler and battery terminal.
(red–red)
Between fuel pump relay 
coupler and engine stop switch 
coupler.
(black/red–black/red)
3 Malfunction or open circuit in fuel 
pump relay.Execute the diagnostic mode. 
(Code No. 09)
Replace if defective.
If there is no malfunction with 
the 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 
causeCheck 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 
defective, the number of the 
faulty cylinders appears 
alternately at 2-second 
intervals.)
Replace ECU if defective.Turning the 
main switch to 
“ON”. 
						

							FUEL INJECTION SYSTEM
7-61
Fault code No. 46 Symptom Power supply to the fuel injection system is not normal.
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Main wire harness ECU couplerCheck 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 
securely.Starting the 
engine and 
operating it at 
idle.
2 Faulty battery.Replace or change the battery
Refer to “CHECKING AND 
CHARGING THE BATTERY” on 
page 7-94.
3 Malfunction in rectifier/regulatorReplace if defective.
Refer to “CHARGING 
SYSTEM” on page 7-11.
4 Open or short circuit in wire harness.Repair or replace if there is an 
open or short circuit.
Between battery and main 
switch
(red–red)
Between main switch and 
ignition fuse
(brown/blue–brown/blue)
Between ignition fuse and ECU
(red/white–red/white)
Fault code No. 50 Symptom Faulty ECU memory. (When this malfunction is detected in 
the ECU, the fault code number might not appear on the 
meter.)
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Malfunction in ECU. Replace the ECU.
NOTE:
Do not perform this procedure 
with the main switch turned to 
“ON”.Turning the 
main switch to 
“ON”. 
						

							FUEL INJECTION SYSTEM
7-62
Fault code No. 62 Symptom Muffler cooling fan temperature sensor: open or short cir-
cuit detected.
Diagnostic code No. 12 Muffler cooling fan temperature sensor
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Installed condition of muffler cooling 
fan temperature sensor.Check for looseness or pinching. Turning the 
main switch to 
“ON”.
2 Connections
Muffler cooling fan temperature 
sensor coupler
Main wire harness ECU couplerCheck 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 
securely.
3 Open or short circuit in wire harness.Repair or replace if there is an 
open or short circuit.
Between muffler cooling fan 
temperature sensor coupler and 
ECU coupler.
(black/blue–black/blue)
(brown/yellow–brown/yellow)
4 Defective muffler cooling fan 
temperature sensor.Execute the diagnostic mode. 
(Code No.12)
Replace if defective.
Refer to “CHECKING THE 
MUFFLER COOLING FAN 
TEMPERATURE SENSOR” on 
page 7-108. 
						

							FUEL INJECTION SYSTEM
7-63
Fault code No. 63 Symptom Engine trouble warning light is flashing. (Abnormally high 
temperature is detected by muffler cooling fan tempera-
ture sensor.)
Diagnostic code No. 12
51
63Muffler cooling fan temperature sensor
Muffler cooling fan motor relay
Stopping the flashing of the engine trouble warning light 
(erasing the muffler cooling fan temperature sensor fault 
code)
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Muffler cover fan fuse or ECU fuse is 
blown.Check the muffler cover fan 
fuse and ECU fuse.
Refer to “CHECKING THE 
FUSES” on page 7-93.Turning the 
main switch to 
“ON”.
Execute the 
diagnostic 
mode. (Code 
No.63) 2 Defective muffler cooling fan 
temperature sensor or motor relayExecute the diagnostic mode. 
(Code No.12 and 51)
Replace if defective.
Refer to “CHECKING THE 
MUFFLER COOLING FAN 
TEMPERATURE SENSOR” on 
page 7-108 and “CHECKING 
THE RELAYS” on page 7-96.
3Positions of muffler cooling fan 
temperature sensor and its 
surrounding parts changed due to 
deformed parts near sensor
Muffler cooling fan temperature 
sensor detected a temperature of 
120 °C (248 °F) or higher.Check that the parts near the 
muffler cooling fan temperature 
sensor are not deformed and 
that the sensor and its 
surrounding parts are in their 
correct positions. Repair or 
replace if necessary.
Fault code No. Er-1 Symptom No signals are received from the ECU.
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Main wire harness ECU coupler
Main wire harness meter assembly 
couplerCheck 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 
securely.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 meter assembly 
coupler and ECU coupler
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. Replace the meter assembly.
4 Malfunction in ECU. Replace the ECU. 
						

							FUEL INJECTION SYSTEM
7-64
Fault code No. Er-2 Symptom No signals are received from the ECU within the specified 
duration.
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Main wire harness ECU coupler
Main wire harness meter assembly 
couplerCheck 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 
securely.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 meter assembly 
coupler and ECU coupler
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. Replace the meter assembly.
4 Malfunction in ECU. Replace the ECU.
Fault code No. Er-3 Symptom Data from the ECU cannot be received correctly.
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Main wire harness ECU coupler
Main wire harness meter assembly 
couplerCheck 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 
securely.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 meter assembly 
coupler and ECU coupler
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. Replace the meter assembly.
4 Malfunction in ECU. Replace the ECU. 
						

							FUEL INJECTION SYSTEM
7-65
Fault code No. Er-4 Symptom Non-registered data has been received from the meter.
Diagnostic code No.——
Order Item/components and probable 
causeCheck or maintenance job Reinstatement 
method
1 Connections
Main wire harness ECU coupler
Main wire harness meter assembly 
couplerCheck 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 
securely.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 meter assembly 
coupler and ECU coupler
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. Replace the meter assembly.
4 Malfunction in ECU. Replace the ECU.