Good day! I just purchased a 2006 Prius with 155k. I had the vehicle checked at the local dealer before purchase and it was given a clean bill of health. While driving it this evening, I noticed the lights on the dash were not illuminating properly when the headlights are on. The instrument cluster and the steering wheel controls are illuminated. The radio, start button, park button, and buttons around the display are not illuminated. I tried adjusting the dimmer switch that is to the left of the steering wheel. When I roll it all the way up to the click position, the instrument cluster is illuminated. Once I roll it down past the click position, the entire dashboard goes blank and the center display dims slightly. None of the other lights illuminate. When going over a bumpy patch, I noticed the lights would briefly illuminate and then go off. I also noticed the lights would sometimes briefly illuminated when I would mess with the headlight stalk (turning the headlights on or off or the fog lights on or off). Could it be a fuse? The dimmer? The light control stalk? I would appreciate any advice. Thanks.
The issue probably is not a fuse since the lights intermittently work. You might have a loose wiring harness connection at the headlight switch or perhaps the switch itself. You might also remove the instrument panel plastic to get to the dimmer switch and make sure the wiring harness connector to the switch is fully engaged.
It is not too hard to take the top and bottom covers off the steering column. Look at the headlight combination switch. It is not possible to do much without a meter and schematics, but it sounds like you might get lucky and find the problem by "intelligent wiggling", if it comes and goes with bumps.
