Sym Citycom.300i, Service Manual

Page: 67 / 270

4. Fuel Injection System
4-21
TW Sensor (Engine Coolant Temperature Sensor)
Resistivity measurements
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.
●
Use of the "meter" Ohm stalls, inspection sensor resistance.
Detection judge:
Resistance value and the temperature between relationships as follows:
Temperature
(℃)
Resistance value
(KΩ)
-20 18.8 „ 2.4
40 1.136 „ 0.1
100 0.1553 „ 0.007
Treatment of abnormal phenomena:
●
Temperature sensor damage or couplers to poor contact.
●
Check whether the abnormal wire harness lines.
●
Temperature sensor anomaly, the proposed replacement of the
temperature sensor.
To this chapter contents