The temperature indicator works from a sensor. As a rule, the coolant temperature sensors in a car do not require any maintenance. But often a car enthusiast creeps in doubt about the correctness of his testimony. And a faulty temperature sensor can cause engine breakdown, the repair of which will result in a tidy sum. In this case, check the correctness of its readings.
It is necessary
tool kit, tester, hot water, 100 ohm resistor
Disconnect the engine coolant temperature sensor connector with the engine off. Take a 100 ohm resistor and connect it to the temperature sensor connector. Then turn the ignition on by turning the key. If the temperature gauge is in good working order, the arrow on it should show 90 ° C. The engine must be cold when performing this work. If the arrow on the dashboard shows nothing, ring the wiring leading to the temperature gauge. In the event that the wiring is intact, and the pointer does not work, just replace this device - the problem is in it.
If the gauge is working properly, connect the connectors to the coolant temperature sensor. Start the engine and let it warm up completely. If the temperature gauge does not show anything, or its readings do not correspond to the normal engine temperature, the problem is in the sensor itself, replace it.
There is another way to check the temperature gauge. Disconnect the negative battery terminal on the vehicle. Drain the antifreeze from the engine so that it does not spill when you unscrew the sensor. In this case, the engine must not be hot. Slide the protective sleeve off the harness that fits the sensor and disconnect it from the connector to which it was connected.
Using a wrench, carefully loosen the sensor and then unscrew it from its socket. Take a tester, adjust it to the ohmmeter mode. Connect one contact to the sensor lead and the other to the sensor body. The tester should show a resistance of 700-800 ohms at room temperature. When the sensor is immersed in hot water, its resistance should decrease, and as the water cools down, it should increase again. If this does not happen, the problem is in the sensor. In the event that the sensor is intact, call the wiring and, if necessary, change the temperature gauge.