2001 kia power serge

my 01 kia sometimes has a bad power surge when I hit the brakes at night, it cuts off the radio for about 2 sec. and the dash and head lights dims, What could be the problem?

I would check the brake lights ground return; run a new ground wire from rear lights to engine block/battery negative. I'd do the same for headlight ground. ..then report.

The brake light ground return, where is that located? under the dash, or by the brake lights?

fixed it. It was a bad alternater and faulty battery connection.