when i turn headlights on the dash board lights go off
Check your dimmer to see if you accidentally dimmed them to nothing. In daylight, the dash lights up so you can see it and is not able to be dimmed. With headlights on it can be adjusted, dimmed, to your preference
Search Toyota Prius Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Toyota Prius Experts