Need some help on adding a temp guage to my 2155

[BryanM]

My 2155 electronic temp guage is not accurate. (always says its overheating and its not) I tried a new sending unit and no luck.

I have aprox 3.5 volts at my wire when I check voltage at sending unit. when I disconnect wire from sensor (open circuit) guage reads all the way cold, when I ground circuit it reads all the way hot. which leads me to believe sending unit is bad. So I replaced. And no luck so I think in my guage their is a short at a certain temp the guage shorts to ground, causing needle to go hot.

So Instead of replacing a very expensive guage I thought I would add an aftermarket one. Do they make a add-on electronic guage? Or should I just get a capsile type? How accurate are they? where do I get either?