Engine Coolant Temperature (ECT) Gage

The Engine Coolant Temperature (ECT) Gage is operated by two coils. Battery voltage is applied to both coils. The "C" coil is grounded directly and the "H" coil is grounded through the Engine Coolant Temperature Sensor. The resistance of the Engine Coolant Temperature Sensor is 44 Ohms at 260°F (125°C) and increases at lower temperatures. The resistance is approximately 1365 Ohms at 100°F (37°C). The current through the Engine Coolant Temperature Sensor and the "H" coil increases as the coolant temperature increases moving the pointer to a higher temperature indication.