ENGINE CONTROL 3-15
CYLINDER TEMPERATURE SENSOR
FUNCTION
The cylinder temperature sensor is installed on cylinder and used
to detect the cylinder temperature.
This is a thermistor type sensor (resistance of which changes
depending on the temperature) and inputs a signal to the CDI
unit as a voltage value.
This input signal is used to detect engine over-heat as the CDI
unit detects both the temperature and temperature change gra-
dient (temperature rise VS time).
FAILURE SYMPTOMS
• No over heat detection function.
TESTING CYLINDER TEMP. SENSOR
[ 09930-99320 : Digital tester
U Tester range :
(Resistance)
1. Remove the cylinder temp. sensor from cylinder.
2. Connect tester probe to sensor lead wires as shown.
3. Immerse the sensor’s tip in water and gradually heat the wa-
ter while monitoring the changes in sensor resistance.
Check if resistance indicated matches specification.
Sensor resistance:
Tester probe connection
Red (+) Black (–)
Violet
Black
0.33 – 0.45
Water
tempera-
ture °C(°F)
75 (135)50 (122)25 (77)0 (32)
Resistance
k
0.73 – 0.961.8 – 2.35.3 – 6.6
Thermometer
Heater
25
Temperature
75 (°C)
kΩ
Resistance
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