2017 Three just turned 50k miles. I noticed yesterday that the auto headlight display on the dash was not showing the auto below the headlight light. I leave the auto high beams engaged all the time. The blue high beam indicator light was on which it does not do when the auto high beam is activated. The blue indicator light on the auto headlight button to the left of the lower dash was not on. I pushed the auto headlight button and it did not turn off the high beam indicator light or display the auto indicator below the headlight light. The blue light on the switch was not on. I toggled the high beam stalk to the rear and it turned the high beams off. I tried holding the auto high beam headlight button in and that turned the auto on, turned the high beam off and the blue light on the switch button was on. As soon as I let off the auto high beam button the high beam light came back on, the auto was off and the blue light on the button was not on. It seems that the auto headlight switch may have gone bad. Has anyone else had a problem like this with their auto headlight system? I’m thinking that it would be plug and play to replace the auto headlight switch button.
I think you are looking at the situation described here. There's a version of the switch that includes a left button for HUD, and version with a blank on the left side for cars without the head-up display. The part number given in the link above is for the without-HUD version. Toyota, for understandable reasons, explicitly discourages any attempts at repairing an electrical switch, and says to just replace it. Nevertheless, if this happened in my car, I am pretty sure I would at least glance at the switch I took out to see if I could spot a simple mechanical reason it wasn't latching in.
