Temperature gage not working,gas,gears gage are ok.

My 2002 grand prix 3.8 temp gage stays around 80 , is this normal, what should it read at?

I just had a similar issue with my 1995 Buick century. My issue started out with the gage being almost pegged with the car off. When I turned the key to run it pegged the gage completely. I first called AutoZone and they told me it was either the temperature sensor, thermostat, or gage.
I knew that my thermostat wasn’t bad because I replaced it a while back. I then checked my sensor; I unhooked the two pin connector of this sensor at the block and suspected the needle to drop to zero. This was not the case.
I then checked my wires using a multimeter to verify that there was no short at my firewall. My wiring was fine.
I then called a family mechanic and he instructed me that there is also a "temperature switch" that also is interconnected to the coolant temperature gage. I then found this switch which was threaded into the block near the firewall of my car. I unhooked the 2 pin connector and suspected that the gage would return to the neutral position. And sure enough it did!!
This could have been a heck of a lot easier if AutoZone could have told me that my car has a "temperature switch". But non the less it was only a $15 fix!

First try unhooking your sensors and switch to see if this is the problem, I would lastly suspect your gage to fail!

Good Luck

The problem must be with your radiator temperature sensor; temperature changes are registered as resistance changes, and for your gauge to read either extreme means and open or a short. Both require replacement.
Quick test: Take the wires off the radiator temp sensor and short them, If the gauge reads over-temp, then you proved the sensor is good.

Located the temp sending unit check that its pluged in, if it is unplug it and ground the wire to something metal (with the switch on) and see if the gauge moves if it does then your temp sending unit is bad and needs replaced

May have a bad temp. Sensor or broken wire at sensor make sure coolant is full