Checking The Air Temperature Sensor - Yamaha F150A Service Manual

3. Measure the pulser coil output peak volt-
age.
TIP:
• When measuring the pulser coil output
peak voltage under the cranking (unloaded)
condition, disconnect the coupler "a" to pre-
vent the engine from starting.
• When measuring the pulser coil output
peak voltage under the cranking (loaded)
condition, remove the clip from the engine
shut-off switch to prevent the engine from
starting.
W/R
B
W/B
W/R
a
a
1
Test harness (3 pins) "1": 90890-06791
Pulser coil output peak voltage:
White/Red (W/R)–Black (B)
White/Black (W/B)–Black (B)
Unload-
ed
r/min
Cranking
DC V 3.5
4. Disconnect the special service tool, and
then measure the pulser coil resistance.
Pulser coil resistance:
White/Red (W/R)–Black (B)
White/Black (W/B)–Black (B)
459.0–561.0 Ω at 20 °C (68 °F)
5. Connect the pulser coil coupler.
W/R
B
W/B
B
W/B
1
Loaded
1500 3500
3.0 21.0 39.0

Checking the air temperature sensor

1. Measure the ambient temperature.
2. Connect the YDIS to display "Intake air
temperature".
3. Check that the difference between the
ambient temperature and the displayed
intake temperature is within ± 5 °C
(± 9 °F).
TIP:
• Check the air temperature sensor when the
engine is cold.
• When checking the air temperature sensor,
remove the top cowling and do not start the
engine.
4. Disconnect the air temperature sensor
coupler "a".
5. Turn the engine start switch to ON, and
then measure the input voltage at the air
temperature sensor coupler.
B/Y
B
Air temperature sensor input voltage:
Black/Yellow (B/Y)–Black (B)
4.75–5.25 V
6. Turn the engine start switch to OFF, and
then remove the air temperature sensor.
7. Place the air temperature sensor in a
container of water and heat the water
slowly.
8. Measure the air temperature sensor
resistance.
5-23
Ignition unit and component
a