2006 YAMAHA YZ250F THROTTLE POSITION SENSOR

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THROTTLE POSITION SENSOR SYSTEM
THROTTLE POSITION SENSOR SYSTEM
INSPECTION STEPS
If the throttle position sensor will not operate, use the following inspection steps.
* marked: Refer to “IGNITION SYSTEM” section.
NOTE:
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112
Check entire ignition
system for connection.Repair or replace.
Check throttle position
sensor.Throttle posi-
tion sensor coilReplace.
*Check CDI magneto. Charging coil Replace.
Check CDI unit.Throttle posi-
tion sensor
input voltageReplace.
OK
OK
OK
No good
No good
No good
No good

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–+ELECTHROTTLE POSITION SENSOR SYSTEM
HANDLING NOTE
CAUTION:
Do not loosen the screws (throttle position
sensor)
1 except when changing the throt-
tle position sensor due to failure because it
will cause a drop in engine performance.
1
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
•Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
THROTTLE POSITION SENSOR COIL
INSPECTION
1. Inspect:
•Throttle position sensor coil resistance
Out of specification → Replace.
Tester (+) lead
→ Blue lead
1
Tester (–) lead
→ Black lead
2
Throttle posi-
tion sensor coil
resistanceTester selector
position
4 ~ 6 kΩ at
20 °C (68 °F)kΩ × 1
2. Loosen:
•Throttle stop screw 1
NOTE:
Turn out the throttle stop screw until the throt-
tle shaft is in the full close position.

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–+ELECTHROTTLE POSITION SENSOR SYSTEM
3. Inspect:
•Throttle position sensor coil variable
resistance
Check that the resistance in increased as
the throttle grip is moved from the full
close position to the full open position.
Out of specification → Replace.
Tester (+) lead
→ Yellow lead
1
Tester (–) lead
→ Black lead
2
Throttle position sen-
sor coil variable
resistanceTester
selector
position
Full
closedFull
opened
k
Ω
× 1
Zero ~ 3 k
Ω
at 20 °C
(68°F)4 ~ 6 k
Ω at
20 °C
(68°F)
THROTTLE POSITION SENSOR
REPLACEMENT AND ADJUSTMENT
1. Remove:
•Throttle position sensor coupler
•Carburetor
2. Remove:
•Screw (throttle position sensor) 1
•Throttle position sensor 2
NOTE:
Loosen the screws (throttle position sensor)
using the T25 bit.
3. Replace:
•Throttle position sensor
2
1
4. Install:
•Throttle position sensor 1
•Screw (throttle position sensor) 2
NOTE:
•Align the slot a in the throttle position sensor
with the projection b on the carburetor.
•Temporarily tighten the screws (throttle posi-
tion sensor).
b
a
2 1

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–+ELECTHROTTLE POSITION SENSOR SYSTEM
5. Install:
•Carburetor
•Throttle position sensor coupler
6. Adjust:
•Engine idling speed
Refer to “ENGINE IDLING SPEED
ADJUSTMENT” section in the CHAPTER
3.
7. Insert the thin electric conductors 2 (lead)
into the throttle position sensor coupler 1,
as shown, and connect the tester to them.
CAUTION:
Do not insert the electric conductors
more than required because it may
reduce the waterproof function of the
coupler.
Make sure that a short-circuit does not
develop between the terminals because it
may cause damage to electrical compo-
nents.
8. Start the engine.Tester (+) lead
→ Yellow lead
3
Tester (–) lead
→ Black lead
4
9. Adjust:
•Throttle position sensor output voltage
Adjustment steps:
Adjust the installation angle of the throttle
position sensor 1 to obtain the specified
output voltage.
NOTE:
Measure the output voltage accurately with
a digital electronic voltmeter that gives an
easy reading of a small voltage.
Throttle posi-
tion sensor out-
put voltageTester selector
position
0.58 ~ 0.78 V DCV

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10. Put the aligning marks a on the TPS and
carburetor.
11. Stop the engine.
12. Remove the carburetor.
a
13. Tighten:
•Screw (throttle position sensor) 1
NOTE:
Tighten the screws (throttle position sensor)
using the T25 bit.
14. Install the carburetor.1
THROTTLE POSITION SENSOR INPUT
VOLTAGE INSPECTION
1. Disconnect the throttle position sensor cou-
pler.
2. Start the engine.
3. Inspect:
•Throttle position sensor input voltage
Out of specification → Replace the CDI
unit.
Tester (+) lead → Blue lead 1
Tester (–) lead → Black/Blue lead 2
Throttle posi-
tion sensor
input voltageTester selector
position
4 ~ 6 V DCV-20
THROTTLE POSITION SENSOR SYSTEM