When I turn on my 2010 headlights, my gauge lights dim, when lights are off, gauge lights are very bright? I do not believe it has always been this way,
yep, that's the way it is/ but, you can adjust the brightness/ Dashboard Display Brightness? | PriusChat
It's designed for the dash display to have less back lighting at night when it's less needed. Turn your dash light brightness all the way up until it clicks and you have daylight illumination when headlights are on. Posted via the PriusChat mobile app.