I have a '91 Sedan DeVille. When I apply the brakes the instrument panel is dimming. In addition in the past couple of days I have had two incedents where after applying the brakes the radio made a "popping" noise and the Anti-Lock brake light came on. I had the brakes done about a month ago and have not had any problems with them and the most recent change was new tires put on a couple of days before this started happening. I am also hearing a high pitch hum when applying the brakes at low speed. Any advice or information would be appreciated.