Engine Coolant Temperature Gauge

The engine coolant temperature is operated by two coils. The battery voltage is applied to both of the coils. One of the coils is grounded directly and the other coil is grounded through the engine coolant temperature sender. The engine coolant temperature sender has a resistance of 44 ohm at 125°C (260°F). The resistance increases at lower temperatures. The resistance is approximately 1365 ohm at 37°C (100°F), causing the current through the engine coolant temperature sender at one of the coils to increase, as the coolant temperature decreases and moves the pointer.