the connection under the VX that connects to the Transfer case shorts when wet.
Usually when more than just a light shower such as we get here in the western United states. More along the lines of a Thunderstorm such as the Southern United States gets or a Thunder Storm or when you take it Swimming.
OR if it wasn't properly sealed from the factory and just normal road splash splashed up on the connector and it shorted out and the TOD light came on.
If the light is steady and on nothing too bad is happening. If the light is flashing you have major problems. Stop the VX and turn it off Immediately and seek repairs immediately. This is the same for the Check Engine light.
But, best to seek to fix it all the same immediately. But, in a urgent situation you could drive it if the light is steady and not flashing. But, your choice.