Trailer lights fuse

[Rawze]

With a short like that, as a last resort, I use my el-cheapo 75-amp battery charger with it set on trickle charge (10 amps), it going through a couple of cheap-o 100-ft spools of #12 wire from the hardware store on the circuit with no fuse (to limit the current even more). An old 100-ft drop cord works instead of a spool of wire too. - After wrangling on sh?#it and trying to find the intermittent connection for about 3-5 minutes, I can usually follow and see the wire slightly warm all the way to the short using my thermal camera.