It all comes down to the settings in the ECU, which can be adjusted by Toyota. You already provided your own hints from your original post by saying a ) In auto, the low beams never come on automatically b ) In auto, sometimes only the parkers come on when it's dark enough to need the low beams It sounds to me like the switch point is far too dark in the ECU settings, so when it should be time for low beams the ECU is only thinking it's just dark enough to only need the parkers. As in all your posts when in auto the only results you have seen are either no headlights, or parkers only.