Hi guys wondering if anyone could help me solve this issue im having.

When I press on the brakes and my headlights and dash lights are turned off my whole dash, gauges and top brake lights flash bottom brake light does not flash,
but when I turn my headlights on which turns on my dash lights for the climate controls and step on my brakes the flashing doesn't happen.

if anyone can help me figure out this issue it would be great THX!!!