The interior lights began flickering about a month ago while I was driving my 99 gmc sierra. I used the dome overide to keep it under control if it was dark. Now all of the lights flicker and do not shut off even when the vehicle is turned off. I even removed the head lamp and interior lamp control switch out of the dash and the lights continued to stay on. The only way to shut them off was to disconnect the battery. Does anyone have any suggestions. Thanks.