Temperature gauge stuck wide open.

[72timemachine]

Hello,

As the title suggests the temp gauge is reading all the way past 260 degrees. Now, I am familiar that there is a difference between the coolant sensor (two wire connector located near the thermostat housing) and the temperature sensor ( single green wire located between cylinders 1 and 3 on the driver's side cylinder head).

I did clean both the green wire's metal connector and the temperature sensor's single connection prong with a wire brush and some fine sandpaper to insure a good clean connection, however, the temp gauge is still reading 260 degrees if the key is turned in the on or off position. It does not matter if the engine is hot or stone cold, it's always at 260 degrees.

Is there a way to test the temp gauge if I dig it out of the dash cluster or has someone experienced this same problem and had to replace the gauge. Is there also a way to test the temperature sensor if I remove it from the cylinder head, I have a multimeter. I tried to search for old posts on this topic but did not find too much on this topic so if anyone has a good post covering this exact problem, that would be great.

Thanks for any help, much appreciated.