It's a 2000 cherokee auto i6 during the day when I have headlights off I press on the brake pedal and my radio and mileage numbers dim down and now today when I was driving to work whenever I used the turned signals the radio and mileage numbers would blink in unison to the blinkers what would cause this?

 

Do you have trailer wiring spliced into your tailights ? I had a similar problem .. The jeep thought I was turning my lights on every time I hit the brakes because of a back feed to the tail lamp wiring