My Dashboard backlight is not illuminating correctly, it’s usually on when I start the car and turn my lights on but as soon as I move it turns off, then doesn’t come back on until I hit over 60mph at which point it quickly flashes on and goes back off as soon as I stop accelerating. All the gauges work absolutely fine the whole time and i’ve checked all of my lights which work. I’ve only recently had a new alternator too. Any ideas?