Why doesn't the heater get hot and the temperature gauge is on hot? on 1998 Toyota Tacoma

I noticed that my heater was blowing cool air snd then the needle for the temperature went up to hot. When I turned off the heater the temperature went down some.

Asked by for the 1998 Toyota Tacoma
Does the engine actually get as hot as the gauge shows?
The engine did not overheat but the needle was on hot.
Sounds like a grounding issue; Check and clean all your grounds before going further, and coolant level.