Engine temp Cold in cold highway driving???

93 camry V6 (3VZ-FE) new radiator 15,ooo miles ago. Temp gauge drops down below C when driving in high speed cold weather. Climbs back to normal when engine is worked on hills, then back to C. Temp sensor appears to be on water inlet tube before thermostat. If is the case, then the gauge would react as mine does, only seeing coolant in front of a closed thermostat. Question; doesn't the engine rely on the temperature sending unit for engine management? Those in the know, please comment. Thanks.

93 camry V6 (3VZ-FE) new radiator 15,ooo miles ago. Temp gauge drops down below C when driving in high speed cold weather. Climbs back to normal when engine is worked on hills, then back to C. Temp sensor appears to be on water inlet tube before thermostat. If is the case, then the gauge would react as mine does, only seeing coolant in front of a closed thermostat. Question; doesn't the engine rely on the temperature sending unit for engine management? Those in the know, please comment. Thanks.
The temp sensor that sends readings to the ECU is a different one than the one that sends the info to the indicator that you see.

The temp sensor that sends readings to the ECU is a different one than the one that sends the info to the indicator that you see.

So am I correct that the gauge reading fluctuates from "C" to about 30% depending on the air temperature. All cars I've owned get to operating temperature and stay there. Thanks.

Temp gage should get to about half way up and stay there--even in cold weather. Sounds like you need a new thermostat.

My 89 was doing the same thing... I replaced the thermostat and that fixed it.. I now also get better fuel milage.

There was no thermostat!!! I quess you really can't trust anyone! Replaced the thermostat with a new Toyota one and the car runs perfect. Thanks to all that responded.