I have a 1997 Ford F150 4.6 and the temp. gauge is pegging out all the time. I can unplug the sensor and it stays at pegged out. Everything else in my cluster works fine. And is there only 2 sensors for the temp 1 for computer and 1 for the gauge. If any one could help it would be awesome

 

With power off, disconnect the temp sender and check the wire for a short to ground with an ohmmeter.

 

Does it jump or slowly get there? If it is sporadic and all over the place I would say connection/ground issue. If it pegs and then comes back down well.......gaskets

 

Hey, new here, but need help. I have a 97 4.6 with the same issue, turn the key, pegs to hot. I have found 3 sensors, 2 just behind and to the left of alternator, and one under the alternator/intake manifold. Have unplugged all three and the gauge still pegs when I turn the key.
I have a multimeter, but not sure how to check for short to ground.
Any thoughts?

 

I have the same problem you had. I replaced t-stat, radiator, coolant temp sending unit. Heater core. No result. Have you figured out the problem with yours??? Need help.