I have a 2002 Lexus GS 300 couple of days ago I was driving to work at night and I get about 15 minutes into driving all of a sudden if I step on the brakes if I cut my highbeams on everything on the car as far as the lights and on the dashboard would start flickering it only did that once if anybody can help me hit me up

 

check battery voltage and clean the battery contacts

 

Agreed. Check battery terminals and ensure a good clean and tight connection. If that's a good, test the alternator, make sure it isn't going out.