2012 YAMAHA YZ450F sensor

7-29
FUEL INJECTION SYSTEM
4 Continuity of harness Open or short circuit → Replace.
Between injector coupler and ECU
coupler.
(Red–Red)
(Red/Black–Red/Black)Start the engine and let it
idle for approximately 5
seconds.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
5.
5 Malfunction in ECU. Replace the ECU.
Fault code No. 41
Symptom Lean angle sensor malfunction. (the sensor is built into the ECU)
Fail-safe system Unable to start
Unable to drive
Diagnostic code No. D08
FI diagnostic tool display Lean angle sensor
• 1.0 V (Upright)
• 4.0 V (Overturned)
Checking method Remove the ECU and incline it 45 ° or more.
Item Item/components and probable cause Check or maintenance job Checking method
1 Malfunction in ECU. Replace the ECU. Fault code No. 39
Symptom Injection system circuit signal is not received properly.
Fail-safe system Unable to start
Unable to drive
Diagnostic code No. D36
FI diagnostic tool display Actuates the injector for five times every second.
The "WARNING" LED on the FI diagnostic tool comes on each time the fuel injector is ac-
tuated.
Checking method Check the operating sound of the injector five times.
Item Item/components and probable cause Check or maintenance job Checking method

7-35
FUEL PUMP SYSTEM
FUEL PUMP SYSTEM
INSPECTION STEPS
If the fuel pump is not operating normally, perform the following procedures in the order given.
• Remove the following parts before inspection.
1. Seat
2. Side cover (right/left)
3. Fuel tank
• Use the following special tools in this inspection.
Check engine stop switch. No good→Replace.
OK ↓
Checking the couplers and leads connections No good→Repair or replace.
OK ↓
Check the fuel pump.(Checking the fuel pump
body)No good→
Replace the fuel pump assembly.
OK ↓
Replace the ECU.
Pocket tester:
YU-03112-C/90890-03112
Test harness S-pressure sensor (3P):
YU-03207/90890-03207

7-36
ELECTRICAL COMPONENTS
ELECTRICAL
COMPONENTS
CHECKING THE COOLANT
TEMPERATURE SENSOR
1. Remove:
•Coolant temperature sensor
Refer to "REMOVING THE CYL-
INDER HEAD" section in the
CHAPTER 4.
•Handle the coolant temperature
sensor with special care.
•Never subject the coolant tem-
perature sensor to strong
shocks. If the coolant tempera-
ture sensor is dropped, replace
it.
2. Check:
• Coolant temperature sensor re-
sistance
3. Connect:
•Tester
Tester (+) lead → Brown lead "1"
Tester (-) lead → Black/Blue lead
"2"
4. Immerse the coolant temperature
sensor in a container filled with
coolant.
Make sure the coolant temperature
sensor terminals do not get wet.
5. Place a thermometer "3" in the
coolant.
6. Slowly heat the coolant, and then
let it cool to the specified temper-
ature indicated in the table.Out of specification → Replace.
CHECKING THE INTAKE AIR
PRESSURE SENSOR
1. Check:
• Intake air pressure sensor output
voltage
2. Connect:
• Test harness S–pressure sensor
(3P) "1"
•Tester
Tester (+) lead → Pink/White lead
(wire harness color)
Tester (-) lead → Black/Blue lead
(wire harness color)
3. Connect the FI diagnostic tool
sub-wire harness to a battery, and
then set the switch on the harness
to "ON".
When checking the intake air pres-
sure sensor, do not start the en-
gine.
4. Measure the intake air pressure
sensor output voltage.
Out of specification → ReplaceCHECKING THE INTAKE AIR
TEMPERATURE SENSOR
1. Remove:
• Intake air temperature sensor
(from the air filter case.)
•Handle the intake air temperature
sensor with special care.
•Never subject the intake air tem-
perature sensor to strong
shocks. If the intake air tempera-
ture sensor is dropped, replace
it.
2. Check:
• Intake air temperature sensor re-
sistance
3. Connect:
•Tester
Tester (+) lead → Brown/White
lead "1"
Tester (-) lead →Black/Blue lead
(wire harness color) "2"
Out of specification → Replace.
CHECKING THE ATMOSPHERIC
PRESSURE SENSOR
1. Check:
• Atmospheric pressure sensor out-
put voltage
2. Connect:
• Test harness S- pressure sensor
(3P) "1"
•Tester
Tester (+) lead → Pink lead (wire
harness color)
Tester (-) lead → Black/Blue lead
(wire harness color)
B/L Br
Coolant
tempera-
ture sensor
resistanceTester se-
lector posi-
tion
210–220 Ω
(100°C,
212°F)Ω×100
2.51–2.78
kΩ (20°C,
68°F)kΩ×1
Test harness S–pressure
sensor (3P)
YU-03207/90890-03207
Output volt-
ageTester se-
lector posi-
tion
3.4–3.8 V DCV
Intake air
tempera-
ture sensor
resistanceTester se-
lector posi-
tion
5.4–6.6 kΩ
(0°C, 32°F)kΩ×1
290–390 Ω
(80°C,
176°F)Ω×100
Br/WB/L

7-37
ELECTRICAL COMPONENTS
3. Connect the FI diagnostic tool
sub-wire harness to a battery, and
then set the switch on the harness
to "ON".
When checking the atmospheric
pressure sensor, do not start the
engine.
4. Measure the atmospheric pres-
sure sensor output voltage.
Out of specification→Replace.
CHECKING THE RECTIFIER/
REGULATOR
1. Connect:
• Connect the tester to the coupler
for connecting optional part
Tester (+) lead→ Red lead "1"
Tester (-) lead→ Black/White lead
"2"
2. Start the engine.
3. Check:
• Rectifier/regulato output voltage
Out of specification → Replace.
4. Stop the engine.CHECKING THE FUEL INJECTORS
1. Remove:
•Seat
•Fuel tank
• Air filter case
2. Check:
•Injector resistance
3. Connect:
•Tester
Tester (+) lead → Injector termi-
nal "1"
Tester (-) lead → Injector termi-
nal "2"
Out of specification→Replace. Test harness S–pressure
sensor (3P):
YU-03207/90890-03207
Output volt-
ageTester se-
lector posi-
tion
3.4–3.8 V DCV
Output volt-
ageTester se-
lector posi-
tion
14.1–14.9 V DCV
Lg
R
B/W
Injector re-
sistanceTester se-
lector posi-
tion
12.0 Ω
(20°C, 68°F) Ω×10