Ok, sorry I didn't get back to you sooner. But I kept forgetting to get the information.
Clueless is right, if you are getting a low coolant light, there is a sensor in the overflow resevoir. To test that sensor, while the engine is running, smack the resevoir on the bottom and see if the light goes out. A lot of times that sensor will stick and turn on the light. If the light goes out, then that is the source of the problem.
The coolant temperature sensor is located on the left (drivers) side of the engine under the intake. It is probably located near the thermostat housing, if not in it. I don't think that is the source of your problem though. If that sensor fails, the engine would not run properly. That sensor communicates with the computer and if it were giving false readings the engine might not idle.
Let me know if you need more info.