Need some help in trying to figure out why my temperature light on my 71 Monte comes on once in awhile, and stays on for a few minutes, then goes back to normal. I have replaced the sensor twice, put in new wiring the last couple of feet away from the sensor. The car is not heating up and the radiator is always filled. I have replaced the circuit board wiring in the dash about a year ago, and have replaced all the lights/bulbs at that time. This just started to occur about a month ago. When I first start up all the idiot lights come on and then go to normal once the car starts. This one has me baffled. There must be some kind of grounding going on, but how do I find it?