Temperature gauge

I just replaced the head on my 2.6 and upon running the temp gauge isn't moving. I only removed the connection at engine, I checked the thermo unit and the ohms change with a rise in temp and checked the wires getting 4.9 volts across the 2 wires to the sensor and 4.9 v to ground on one wire. Does anyone have an experience with this system? Going to replace the sensor today and see if that makes a difference. Also the manual only 1 wire going to the sensor Yellow-red and I have two one green and the other yellow. Thanks

The temp sensor might need to be grounded on the green wires. Get it up to temp and ground it temporarily and see if you get any movement on the gauge.