Tempreture gauge

[Philip]

Tempreture gauge goes up to normal, then suddenly drops back to cold and then can go back to normal. Garage checked connections, but still doing it. Is it sensor or likely to be gauge itself. Don't want to replace one and find its other. Any thoughts appreciated.
Thanks Philip

[rich]

Hi Philip,

The gauge works by a varying resistance to ground (negative). The way to test it is to ground out the wire, the gauge will go either high or low full scale deflection (The max one way or the other). This will tell you that it is working OK and the sensor is faulty. Best to do this at the sensor so it checks the wiring as well.

Hope this helps.

Rich.