91 z 350tpi, my temp guage hasn't registered a thing for months. Everything is going fine with the cooling system exept for it. When I turn the key it get's power and will max out while the key is in crank position, so its not a short or an open circuit. This morning I had a freak problem and the engine overheated. While bubbling out the reservoir the guage read about 160. I found my underhood light wire hanging down and I disconnected it because I think it was grounding on the runner. I started the car up and everything was wonderful. That's why it was a freak thing and I don't believe it has anything at all to do with the guage not working. So, all has been said, anyone else ever have this problem. Oh yeah, two weeks ago I changed the temp transmitter and the fan switch. I didn't realize the transmitter was for the ECM and the fan switch was melted and broken so it needed to be changed. So basically, what sends the temp to the guage? My Hanes is worthless, a friend is going to get me a shop manual for it, but till then I have no Idea what to do.