2012 YAMAHA YZ450F ad blue

7-15
FUEL INJECTION SYSTEM
3 Continuity of harness Open or short circuit → Replace.
Between the intake air pressure
sensor coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Pink/White–Pink/White)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor.
Make sure that the installation position is cor-
rect.Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.
Incorrect installation position →
Properly install.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.
5 Defective intake air pressure sensor. Execute the diagnostic mode (di-
agnostic code No. D03).
When the engine is stopped,
displays the atmospheric pres-
sure according to the elevation
and weather.
0 m above sea level: Approx.
101 kPa
1000 m above sea level: Ap-
prox. 90 kPa
2000 m above sea level: Ap-
prox. 80 kPa
3000 m above sea level: Ap-
prox. 70 kPa
Check that the value changes
while the engine is being
cranked.
Displayed value is incorrect → Re-
place. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6.
6 Malfunction in ECU. Replace the ECU. Fault code No. 13
Symptom Intake air pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D03
FI diagnostic tool display Intake air pressure
Checking method Crank the engine. (If the display value changes, the performance is OK.)
Item Item/components and probable cause Check or maintenance job Checking method

7-17
FUEL INJECTION SYSTEM
Fault code No. 15
Symptom Throttle position sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D01
FI diagnostic tool display • 15–19° (Fully closed position)
• 95–101° (Fully opened position)
Checking method• Check with throttle valves fully closed.
• Check with throttle valves fully open.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the throttle position sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between throttle position sensor
coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Yellow–Yellow)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor.
• Make sure that the installation position is cor-
rect.
• Make sure that there are no problems with the
installation.Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.
Incorrect installation position →
Properly install.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

7-20
FUEL INJECTION SYSTEM
Make sure that the engine is completely cool before checking the coolant temperature sensor.
Fault code No. 21
Symptom Coolant temperature sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D06
FI diagnostic tool display -20–150°C
Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is the current coolant temperature.
Checking method Check the coolant temperature.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the coolant temperature sensor coupler.
Disconnect the coupler and check the pins
(bent or broken terminals and locking condition
of the pins).Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between coolant temperature sen-
sor coupler and ECU coupler
(Brown–Brown)
(Black/Blue–Black/Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor. Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

7-22
FUEL INJECTION SYSTEM
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
3.
3 Continuity of harness Open or short circuit → Replace.
Between the intake air tempera-
ture sensor coupler and ECU cou-
pler.
(Brown/White–Brown/White)
(Black/Blue–Black/Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
4.
4 Installed condition of sensor. Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
5.
5 Defective intake temperature sensor. Execute the diagnostic mode (di-
agnostic code No. D05).
Cold engine: Displayed temper-
ature is close to the ambient
temperature.
Displayed value is incorrect → Re-
place. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6.
6 Malfunction in ECU. Replace the ECU. Fault code No. 22
Symptom Intake air temperature sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D05
FI diagnostic tool display -20–100°C
Cold engine: Displayed temperature is close to the ambient temperature.
Warm engine: Displayed temperature is approximately 20°C higher than the ambient tem-
perature.
Checking method Check the temperature in the intake manifold.
Item Item/components and probable cause Check or maintenance job Checking method

7-23
FUEL INJECTION SYSTEM
Fault code No. 23
Symptom Atmospheric pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D02
FI diagnostic tool display Atmosphere
Checking method Measure the atmospheric pressure.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the atmospheric pressure sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between atmospheric pressure
sensor coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Pink–Pink)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor. Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

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

8-3
CHASSIS
SETTING OF SPRING AFTER
REPLACEMENT
After replacement, be sure to adjust
the spring to the set length [sunken
length 90–100 mm (3.5–3.9 in)] and
set it.
1. Use of soft spring
• Set the soft spring for less re-
bound damping to compensate
for its less spring load. Run with
the rebound damping adjuster
one or two clicks on the softer
side and readjust it to suit your
preference.
2. Use of stiff spring
• Set the soft spring for more re-
bound damping to compensate
for its greater spring load. Run
with the rebound damping adjust-
er one or two clicks on the stiffer
side and readjust it to suit your
preference.
Adjusting the rebound damping will
be followed more or less by a change
in the compression damping. For cor-
rection, turn the low compression
damping adjuster on the softer side.
When using a rear shock absorber
other than currently installed, use
the one whose overall length "a"
does not exceed the standard as it
may result in faulty performance.
Never use one whose overall
length is greater than standard.
REAR SHOCK ABSORBER
SETTING PARTS
• Rear shock spring "1"
• The I.D. mark "a" is marked at the
end of the spring.
• Spring specification varies accord-
ing to the color and quantity of I.D.
marks.
• Extent of adjustment (spring pre-
load)
For the spring preload adjustment, re-
fer to "ADJUSTING THE REAR
SHOCK ABSORBER SPRING PRE-
LOAD" in the CHAPTER 3.
Length "a" of standard
shock:
459 mm (18.07 in)
TYPESPRI
NG
RAT
ESPRING
PART
NUMBER
(-22212-)I.D.
MARK
SOFT 5.333D-10
Yellow (Blue)
33D-B0
(Red)
* STD 5.533D-20
Pink (Blue)
33D-C0
(Red)
STD5.733D-30
White (Blue)
33D-D0
(Red)
STIFF
5.9
33D-40
Silver (Blue)
33D-E0
(Red)
* Except for USA and CDN
SPRING
PART
NUMBER
(-22212-)
Maximum Minimum
33D-10
33D-20
33D-30
33D-40
33D-B0
33D-C0
33D-D0
33D-E0Position
in which
the spring
is turned
in 18 mm
(0.71 in)
from its
free
length.Position
in which
the spring
is turned
in 1.5 mm
(0.06 in)
from its
free
length.