VESPA GTS Super 125 i.e. Service Station Manual page 108

Electrical system
ENGINE TEMPERATURE SENSOR
Function
Serves the purpose of communicating the engine
temperature to the control unit in order to optimise
performance.
Operation / Operating principle
NTC type sensor (resistance sensor, inversely
variable with temperature).
Pin-out:
1. Ground lead
2. Instrument panel
3. Electronic control unit
4. Ground lead
Engine temperature sensor P0115 - open circuit or shorted to positive / shorted to negative.
Error cause
Open circuit or short circuit to positive: interruption of the circuit or excessive voltage at PIN 13 of the
control unit connector. Short circuit to negative: null voltage between PIN 13 and 7 of the control unit
connector.
Troubleshooting
Open circuit:
- Disconnect the connector of the control unit.
- Measure the resistance value of the sensor at different temperatures between PIN 13 and 7.
- Disconnect the sensor connector.
- Check the continuity of the cable harness between the sensor connector and control unit connector:
Control unit PIN 13 - sensor PIN 3 and control unit PIN 7 - sensor PIN 1. If necessary, restore the cable
harness.
- If the cabling is intact but the sensor resistance value is incorrect, this means that the sensor is faulty
and must be replaced, otherwise proceed with the checks.
Short circuit to positive:
- With the sensor connector and the control unit disconnected, verify that the fault is shorted with the
battery positive of sensor connector PIN 3 (or control unit PIN 13) and restore the cabling.
Short circuit to negative:
- Disconnect the sensor connector.
- Check the sensor connector PIN 3 from ground insulation.
- If there is no ground insulation restore the cabling.
- If PIN 3 is insulated from the ground and the error persists, this means that there is a probable fault
in the control unit.
ELE SYS - 108
Vespa GTS Super 125 i.e.