studolf Posted September 5, 2010 Share Posted September 5, 2010 Just changed the thermostat few days ago, yet the car overheated again today. It's strange how it overheats, where the gauge just goes from middle to the red zone instantly. Sometimes it'll come down to the middle and then shoot back up again, while I'm driving. There's enough coolant. I checked the upper and lower rad hoses. The upper feels hot, while the lower feels warm. So is it really overheating or is it just a faulty sensor/gauge? Link to comment Share on other sites More sharing options...
James Matteu Posted September 6, 2010 Share Posted September 6, 2010 Faulty wiring. Get it fixed, the Coolant Temperature Sending Unit may not be the cause; the wiring is far more susceptible to damage. Trouble shoot the circuit first, then the Coolant Temperature Sending Unit. The Temperature Gauge works by receiving voltage to the needle, Electromotive Force moves it. How much current passes through the needle is controlled by the Coolant Temperature Sending Unit; a thermistor. The ground wire leaving the Temperature Gauge goes out to the Coolant Temperature Sending Unit and the Coolant Temperature Sending Unit housing is where the thermistor is grounded. If you have an open circuit, your temp reads cold in all conditions. If you the circuit grounds to the chassis (or motor) then you get an instantaneous hot reading. So your connection between the Temp Gauge and the Coolant Temperature Sending Unit is damaged and wire it touching ground. Find the break and mend it! Solder and shrink wrap are what I would use. Link to comment Share on other sites More sharing options...
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