1989 Pontiac Firefly. When you turn on the headlights or the parking lights the 15-amp fuse marked tail in the fuse box will blow. This fuse has nothing to do with the headlights, it is the fuse for the dome light and dash lights etc. Once the fuse is blown or you remove the fuse from the circuit. There will be no problem with the headlights and if the headlights are turned off, you will be able to replace the fuse and the dome lights and dash lights will work fine until you turn on headlights. Thanks.