My stock temp guage is flipping out on me. It will read correct then bouce around then read lower than normal. I dont know its the guage or something with my cooling system. I checked my coolant(nothing leaking & full)and no leaks. Could it be my thermastat?

 

my aftermarket gauge did this in my Ford F150 it was the connection bouncing around on the block turns out it was the crimp connector never got crimped

 

Unplug the sender then ground the wire. If the guage pegs the gauge and wires are ok and the sender is bad. If the gauge dosen't peg, start checking wires....

This all assumes that your temps aren't fluctuating to match what the gauge is doing.

 

Check the body ground from the battery negative to the core support. Mine came loose and caused all sorts of odd things to happen to my gauges... things like reading backwards...

 

My gauge has been pegged to hot since I bought it, so does that mean my gauge is fried or do I need to check the wires? Where is the sending unit?

 

Pegged to hot means the wire is shorted to ground somewhere.

Sender is in the driver's side of the head all the way at the back.