Take the dash out and check the connections, sounds like a dodgy connection to me. A simple fix, about 2 hours to clean up and reinstall. I installed my nismo speedo, and then cleaned up about 2 gallons of soy sauce that had been spilt in the dash by the yaccuza, or Hiko's Teryaki Takeaway and Pizzeria. It was dried up, but everywhere behind the dash. Your car could have been in the same industry........
And before you all go making Tokyo reservations for your intimate evening, I made up the restaurant name.............lol