Hyundai transmission temperature sensor, the final solution
 

From 1999 till about 2008 Hyundai uses a little plug in temperature sensor that goes inside the transmission.
I think it was about $400 in 2016 to have the dealer replace it. Bet it's significantly more now.
They like to go bad.
Simply replacing it appears to be a bandaid.
So I relocated it outside the transmission, that way when it goes bad again, I replace it and it takes like 10 minutes.
4cyl and v6 Hyundais appear to use a 12 pin connector, 4 thicker pins in the middle and 4 smaller pins flanking each side. There's only 2 things connected to that plug inside the transmission, solenoids and the temperature sensor. The solenoids read single digit ohms. The temperature sensor reads thousands of ohms. Super easy to find with a multi meter.
Cut those 2 wires where they went to the transmission plug, rerouted temperature to a transmission cooler line and shoved the temperature sensor inside the lines pipe wrap.
Problem solved.
I'll post pictures and part numbers later.