GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Engine Temperature Sensor (ETS)



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. At the calibration point, the contacts are open which turns off the solenoids.

Above Calibration

Open circuitBelow Calibration
Closed circuit.

Click image to see an enlarged view

Fig. Fig. 1: Diesel Engine Temperature Sensor (ETS)