Temp sending units

? There are 2 temp sending units on my 1995 sc 1 on the thermostat housing and the other on the coolant tube running next to the valve cover on the passengers side i understand what the one on the thermostat housing is for but what is the 1 on coolant tube for they are different in and the one on the coolant tube is bigger and has a red ring around close to the top of it?

The sensor at the thermostat provides signal to the temp gauge in the dash, the sensor on the passenger side provides signal to the EEC, which signals the IRCM, which turns on the fans.

they do work "together" so if need be replace them both, $3.98 @AZ MPG went up from 16 to21 for that little **%#

I thought that some t-birds have 3 sensors for coolant temp.

1. The one on the gooseneck sends the signal to the gauge on the dash.

2. The one on the front left of the intake (as you're facing motor) sends the signal for the fan.

3. And, the one on the coolant tube by the valve cover near the shock tower mount on the passenger side is for the automatic temperature control inside the car.

1 and 3 are small and stubby. 2 is about twice as long and has an actual plug connector whereas 1 and 3 have a tiny little plug that goes over a thin piece of threaded rod.