Try unplugging the gauge temp sensor and leaving it unplugged for a day or two while driving it normally. I'm confident it's not an overheating problem. It apears the gauge and light are just lying to you. Baaaad light, bAAAAAAd light. If the light still goes on and off with the sender "disconnected, something in the wiring, and very possibly in the instrument panel, is grounding the circuit. Let me know.
One more thing, IF, after a day or of driving with the temp sender unplugged and the light DOESN'T come on, try grounding the temp sendor connector. Then the light should come on. Again, let me know.
Friday, April 3rd, 2009 AT 7:17 PM