Easy there, big fella, easy. You need to be aware that Toyota made multiple versions of the "subtank switch." The most common are simple momentary contact and thus require additional electronics to properly control the transfer pump.
@george_tlc used to sell a small circuit board that performed the tricks needed, but I think he got out of that business years ago now. And there was also a thread from years past titled something like "aux tank the toyota way" that used the official aux tank Toyota ECU. Whatever your approach you need to understand you're on a journey with several different trails that can lead to a happy ending but that have unexpected twists and turns before you get there. The IH8MUD search feature will lead to hours of informative reading.