From your original post it seems you have proven everything to be ok except for the headlight switch and the integration relay. When you turn the headlights on you should have ground on terminal 14 (red-yellow) wire at what Toyota calls the integration relay which is actually a little module containing two relays, 3 transistors and an integrated circuit. This is just below the dash on the left side - not the headlight relay. With this module disconnected you could turn the headlight switch on and look for the ground with your 12 v test light. If the ground is there I would replace the integration relay (module). Probably a dealer only item
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