Radio Issue

[kramarj]

I have an issue on my dad's 97 F250. When the brake pedal is pushed in the radio display goes blank. I tried turning the headlights on and when they are on the radio stays lit. I should also add that the radio still works, just the display goes blank. I just swapped the confusing aftermarket radio with a stock radio. The aftermarket radio had adapters on it so there was no splicing of wires, just plugged the stock plug ins into a stock radio. Kind of confused. Any ideas?