Sym Citycom.300i Service Manual page 67

TW Sensor (Engine Coolant Temperature Sensor)
Resistivity measurements
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Functional Description:
Powered by 5V DC from ECU. It has the two-pin socket on the sensor.
●
One terminal is for power output, and 1 terminal are for ground.
Its main component is a negative temperature coefficient (resistance
●
temperature rise smaller) thermistor.
Installed in the cylinder head, the engine temperature sensor
●
resistance, with the induction to the temperature change, and
converted into voltage signals sent to the ECU was calculated engine
temperature, ECU accordance with the engine warm up to amendment
the injection time and ignition angle.
Testing Procedures:
Dismantled engine temperature sensor.
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Use of the "meter" Ohm stalls, inspection sensor resistance.
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Detection judge:
Resistance value and the temperature between relationships as follows:
(℃)
Temperature
-20
40
100
Treatment of abnormal phenomena:
Temperature sensor damage or couplers to poor contact.
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Check whether the abnormal wire harness lines.
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Temperature sensor anomaly, the proposed replacement of the
●
temperature sensor.
4. Fuel Injection System
Resistance value
18.8 „ 2.4
1.136 „ 0.1
0.1553 „ 0.007
(KΩ)
4-21