This is on our 2011 Prius IV. My Mom has somehow accidentally turned off the speedometer lights, so that panel is all black and you can't tell how fast you're going, can't see how much gas you have left, etc. Any idea on how to turn it back on? We've looked on the Toyota website and turning the rolling switch to the left of the steeringwheel/below the vent doesn't change anything. Adjusting the brightness under Display on the navigation panel doesn't help either, nor does pressing "info/phone" on the navigation system. Also, if you run your gas down to zero and keep driving because you don't know that you don't have any gas left, will that ruin your battery on the 2011 prius IV?
To the left of the steering wheel is a dial/knob/thingy that controls the interior light brightness. It is possible to turn it all the way down to BLACK. It is also possible to turn it all the way back to BRIGHT. It will click for full brightness and just under that click location is where it syncs to the headlight control for night/day operation. Hope this helps.
Is it just the left side of the display with the speedometer, gas tank, and gear info that is all black? That is, do you still have the HSI portion of the display on the right? If so, you may want to take a trip to your dealership and have it checked out. I had this failure in my 2010 IV and had to have the board that controls the display replaced.
