temp sensor on lincoln mark 4

When i start the car, it starts fine now with the new carb,   however, the engine light stays on for about 4 minutes and buzzes.   so i changed the electronic starter thing over on the fender, and hooked up a oil pressure gauge to make sure it was getting pressure,   60 to 70 psi,  so I'm good there,  

i checked the engine temp sensor, it has a two prong plug with a free hanging wire with a mini spark plug wire attachment,  both are red and white.  but i cant for the life of me, find what that free wire attaches to, its only about 3 inches long, so what ever it is, cant be too far,  

i got the electric  diagram and am attaching but it seems to show the two plugs plus a hanging wire, so what the hell do i do with this thing, if any,

since the engine light measures oil and engine temp, and both seem to be ok,  what else could cause the prolonged buzz an light time.   After it goes off, follow up starts go just fine, engine starts, light goes out,,,,

so does that free plug attach to something or not, and what else could cause that buzz,, those are the two questions.

well, i cant get the pictue to up load,,