Speedo / lights interference possible wiring / earth problem?

[brady1990]

Hi all, new to the forums and fairly new to owning a 172 mk2. I have a problem with the speedo, it originally started not long after buying the car and while driving or when i started the car the speedo would go all the way over to 160/170mph! and clock up the mileage while doing it! Ive now noticed it does it only when the lights are on, and also now when indicating it flicks back and forth with the indicator on! and occasionally if i use the rear heated window all the dash lights and electrics speedo included, cut out ( car still running) usually worse when wet/cold weather. Any ideas or advice on where to start would be great!​