Taillight/gauge light issue

[Young gun]

Hay yall I have a 1978 blazer that has been in my family almost 30 years and all of a sudden it started blowing the taillights/courtesy fuse. The interior lights work fine, I replace the fuse and as soon as I pull the headlight switch it blows it. I rewired the taillight harness because someone had spliced in a trailer plug and it’s still doing the same thing I have disconnected the headlight switch and made a jumper with a fuse and when I plug the jumper from power to the brown wire (parking, side marker and license plate) it blows the fuse I can’t find any kind of knick in the side marker wiring and i removed the license plate wiring when I did the taillight harness where else could I check to find the problem?

 

[Wes Harden]

Sounds like you have hit the usual suspects. It does sound like a dead short, which is normally wiring. Have you noticed and melty looking spots in the loom anywhere ? circuit 9brn wire from switch to the bulkhead connector to fronts. Then from a splice at bulkhead connector to 2nd smaller bulkhead connector to the rear