Trailer has working running lights, no brake lights or turn signals

[HoosierHacker89]

My boat trailer seems to have working running lights, but the brake lights and turn signals are not working. I hooked my vehicle up to my 5x8 utility trailer to see if I had a vehicle or trailer issue. I have working running lights and brake lights and turn signals on my 5x8 utility trailer.

I replaced my wiring harness on my boat trailer for good measure and I took a wire wheel and make sure I had good clean contact on my ground. Advice on what to check next?