Ford: wire harness, electronic adapter, new pig

Question
I have a 200 ford explorer 6 cl I put a new wire harness for a trailer on it and a new pig tail at the tail light and when you step on the brakes the broke lights on the trailer go out.This is a flat 4 plug

Answer
Hello

4 wires

green- right turn
yellow- left turn (I may have these 2 reversed)
Brown is Park/ running lights and
White is ground

make sure white is grounded to the fram on both vehicles.

If the truck uses seperate brake/ turn signal lights, you will require an electronic adapter.

Most likely it is a wiring / ground problem with the trailer.  the park lights are using the brake light circuit for a ground and when the brake lights are activated, the ground goes away.