Overdrive light flashing after driving through a puddle of water?

It sounds like the transmission electrical connector got wet or the vehicle speed sensor. Can I ask if the speedometer is working? If not, I would replace the VSS. We should run the codes as well this guide can help. You can get a CAN scanner (Controller Area Network) from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is a good CAN scanner you can get for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is the location of the sensor in the images below. Also remove the electrical connector to the transmission to see if there is corrosion. Check out the images (below). Please let us know what happens.