I have a 82 corvette which is giving me problems with the temperature gauge reading. The gauge reads around 100 when the engine is cold but as the car heats up the gauge reads into the red. A ir thermometer shows the engine is only about 180. I first replaced the sending unit but I was still having the same problems. I did some research and found the willcox help guide. I checked out the sending unit and the least resistance that it will give is 222 ohms after which it will shoot back up to about 285 after the thermostat opens and then back down to 222 as the engine warms etc. The help guide shows that the gauge needs 219 to read at the first mark so it seems that the sender is pretty close. I took the gauge out of the dash and wired it with 12 volts, ground, and sending unit signal to rule out a wiring problem. The gauge behaved the same way it did in the dash so I ordered a replacement. When the new gauge came in I wired it up off the car the same way as I tested the old unit and it still read hot while the car is running a normal temp. I checked the sending unit again and it still seems to be functioning properly. If anyone could give me some advice it would be greatly appreciated.