testing a water temp gauge

• 2023-09-26

When starting a cold car, the pointer type water temperature gauge should indicate the lowest value, and the numerical display of the water temperature gauge should be close to the temperature; After the engine starts, the water temperature should gradually rise. Under the current temperature in the south, it should rise to 80 to 90 degrees Celsius within about 20 minutes, and the time to reach this temperature range in the north may increase by a few minutes. If the above situation is met, it can be considered that the instrument is good. Otherwise, if the cold car water temperature value is too high, the temperature remains unchanged, the temperature is low, and the temperature is high and low, it can be considered that the water temperature gauge has a problem. The reasons for the problem include instrument problems and water temperature sensor problems. Entering the instrument system with the instrument and selecting to perform component testing is good if the instrument can rotate. Remove the water temperature sensor and soak it in hot water. Use a multimeter to measure the wiring point at the back.

The water temperature gauge is an instrument that displays the temperature of cooling water, in degrees Celsius (Celsius). Its sensor is a thermistor type sensor that is threaded onto the engine cooling water channel. The thermistor determines the amount of current flowing through the coil winding of the water temperature gauge, thereby driving the pointer of the gauge to swing.

The detection methods for the quality of a car water temperature sensor are as follows: 1. Check the power supply voltage: unplug the plug and use two multimeter probes to check whether the voltage between the two wires is around 5V of the reference voltage (some models directly supply 12V voltage to the water temperature sensor); 2. Reading data stream: The normal water temperature signal is generally around 95 ℃ (for high-temperature engines , it is around 115 ℃). If the water temperature sensor signal is detected to be abnormal, maintenance should be carried out. For example, if the water temperature signal displays -40 ℃ , it indicates an open circuit or a short circuit to the negative electrode . If the signal does not change at 130 ℃, it indicates a short circuit to the positive electrode (some cars may display it at 140 ℃) .