It’s a 1999

 

Only one temp sensor in your truck, either by the heater hose on the passenger side, or, just to the drivers side of the thermostat housing. Two-wire sensor. Check and make sure it is still plugged in good, and hasn't fallen apart......

 

I just changed that sensor a few months ago. It worked no problem up until I did the radiator flush.

 

Check it, make sure it is still plugged in good.