2001 Park Avenue No Taillights
 

My dad's rig has no taillights, dash lights , and marker lights. I found a blown park lamp fuse. I replaced the fuse and it blew as soon as I turned the headlight switch on. I have checked all of the bulbs and have found nothing wrong. The dash gauges work but I cant see them at night. I can turn the interior lights on with the headlight switch but I cant get the dash lights to come on or dim using the headlight switch. The brake lights and turn signals work but no taillights. I also checked the light control module circuit board to see if I could find any burnt resistors and have found nothing that looked damaged. Any help would be appreciated.