Fuse #4 Taillights Keeps Blowing

[epplecc]

I have looked at the other forums on this topic and nothing seemed to help. But, long story my taillight fuse #4 keeps immediately blowing when I switch on the headlights. I unplugged everything I thought was running the same circuit. (Taillights, license plate lights, headlights, side markers) The fuse still blew. I have a good amount of modifications done, aftermarket headlights and taillights, replaced flasher relay for led turn signals. I completely removed the 4th brake light/backup light and don’t have that wiring connected to anything, but I thought that runs on a different circuit? I haven’t rewired the DRLs for my headlights but I didn’t think that would affect my tails either. I’ve left my side markers unplugged for a while but re-plugging them in didn’t fix the fuse either. No condensation, all bulbs seem to be in good condition. I'd like to see if there are any other simple things that could be the issue before I start tracing through all of the wiring. Thanks.

[NoHaveMSG]

Remove the fuse.............

J/K

You should be able to check for a short to ground from the fuse panel. Pull the fuse, set multimeter to VDC. Key on and check which side of the fuse has power. Then switch multimeter to continuity and check the unpowered side to a chassis ground. If it reads OL then there LIKELY is not a short. If you get a low ohm reading it is shorting to ground.

Should probably call up @soundman98 to check my method though.