Trailer Plug fuses

[HCO41]

After changing the plug from a flat 4 to a 7 pin on my light trailer, I found that I must have blown a fuse when testing truck receptacle to properly wire 7 pin plug I added to trailer. The problem is that now the trailer brake lights and the left directional signal don't work, (right signal works). I tested the truck receptacle and found no power to the left directional terminal in the receptacle. I checked fuse 14 under the hood and found the fuse to be OK. Is there a Maxi fuse or fuseable link up-stream that I should check? With trailer disconnected, I checked lights with external battery and all work fine.

Fortunately all lighting on truck continues to work properly.

Any suggestions???