Check the 6 pin connector below the coolant reservoir on the front of the transmission. Pins 3&5 are for the speed output sensor and there is a known issue where moisture can get into the connector and cause corrosion.
I just had the misfortune of the pins corroding off the end of the transmission harness so I will have the drop to pan and replace it. I was able to de-pin the main harness side and pull the broke pins out and clean all the green corrosion from the connector.
I hope this helps I’ve been researching this issue for days and nobody has replied with a fix. Here is a link to a YouTube I found, inspect your connectors closely I overlooked the two missing pins about 3 times before I finally pulled enough slack to get the connector out to where I could closely inspect it. Mine was from a leaky coolant reservoir, the coolant was dripping on top of the connector.
https://youtu.be/v4_1RJUcjI4