What year of Toyota, motor and Carb/EFI? Cause on my 22RE, my sending unit isn't in the T-Stat housing. It's back in the middle of the intake where it bolts to the head.
Here's a picture I stole offline.
Check to see if the wire isn't broken. When I got my truck the sensor wire that goes to the T-Stat housing, was broke, and I had to solder and repair it.
