So, I couldn't find any answers for this little problem i have...My temp gauge works, to an extent. Basically what it does is it will show a difference in temperature as the engine heats up, but only to the 1/4 mark (or the mark between the 100 and 210). This is kinda hard to explain, but basically my entire gauge is to scale within the 1/4 mark. if it sits halfway between the 100 and the 1/4 mark, I know it's at the right temp. How do I know? It's overheated before and I've gotten some steam from the engine, at which point it was a hair over the 1/4 mark. Now, my question is would this be the coolant temp sensor, sending unit, or the actual gauge?

 

my vote is the temp sending unit

 

x2. Check the sending unit's ground and power supply with key "On."