Circuit Description: Notes
WARNING: This page is about a different car, the 2004 Suzuki Swift + and 2004 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects that the difference between the actual coolant temperature and the start-up coolant temperature is less than a threshold, this DTC sets.
The following table illustrates the difference between temperature, resistance, and voltage:
DTC P0115
| ECT | ECT Resistance | ECT Signal Voltage |
|---|---|---|
| Cold | High | High |
| Warm | Low | Low |