See Figure 1
The engine temperature sensor has two terminals. Twelve volts are applied to one terminal and the wire from the other terminal leads to the fast idle solenoid and Housing Pressure Cold Advance solenoid that is part of the injection pump.
The switch contacts are closed below 125°F (52°C). At the calibration point, the contacts are open which turns off the solenoids.
- Open circuit.
- Closed circuit.