I have no 12V power to my toad signal and brake lights.

I would check the TOAD as in frog ground connection!

If you're unable to track down the fault, try the Tekonsha Modulite ZCI.

Test Lamp at NAPA

I recommend this tool for many things. If you have a 12 volt side of life issue this tester, which has a small incandascant lamp (like a dash indicator lamp) in the clear handle. is a godsend. It puts a small load so it will find a bad connection when a volt meter will not, and it has basically 3 states Bright, Dim, Dark (Bright is good dim = bad connection dark = no power)

Start by testing a known good spot (battery)
Then ground the clip and with the lights on touch the two windows on every blade fuse

Dark-Dark Not the fuse you are looking for (Star Wars pun)
BRIGHT-BRIGHT good fuse
Bright-Dark or Dark-Bright BINGO

I am guessing you have a Ford E450:
Fuse block locations

I do not have a "toad", but one time I lost 12V on my 5er. I traced the wires from my battery and inside my front storage area was an in-line fuse. You might have the same situation. Look carefully, because it is hard to find. I would say it was about 2' from the battery. Good Luck!