4 Pin To 7 Pin Trailer Adapter Installation. Cut the four-pin plug off of the trailer harness. Are the trailer tail lights LED?
There should be a common color for both the tail lights. I am not sure how to make this adapter? I had no choice but to install the wiring while my boat was on the trailer, and having to work underneath my boat made the job a little more difficult, but if your trailer is empty, installation is much easier.
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The three additional pins are: trailer brakes, back-up lights and trailer battery charging. There should be a common color for both the tail lights. I am not sure how to make this adapter?