AXN temperature sensor issues?

My DIL's car has the transmission temperature sensor light go on when the AC is turned on. It also now does so after driving for a relatively short distance (5 miles or so).

The car is a 2000 Taurus 3.0 4V with the AXN transmission. The car has
~150k on the odometer. As far as I know it has never had a tranny D&C. The transmission fluid is clean and full. It has no problems shifting at all or slipping, etc.

I have a FSM.
EDIT yet again C199 pin #9 circuit #359 gray/red wire goes to pin #91 (signal return) on the PCM. The other wire goes from pin #5 of C199 circuit #923 an orange/black wire to pin #37 of the PCM (transmission sensor input signal)


Since no permanent DTC has ever set yet how do I determine what is wrong? Do I have a bad temperature sensor? Or do I have tranny fluid that is getting too hot?

What I cannot find is what the ohms values are or should be?

EDIT! -> I also read when the transmission fluid temp goes up the electrical resistance goes down. So if that is true, if you measure the ohms at pin #91 of the PCM and it is high then it should drop as the transmission fluid gets hotter.
One bit I read was that the engine temp sensor will not allow the transmission to shift into OD if the transmission fluid is too cold.
If it does then does that indicate that the sensor could be junk?

What are the ohms or voltage values??

SECOND EDIT! The light does come on now even thought the AC is off.