jvalich wrote:
You need the 5th pin active (energized by the backup lights) ONLY of you have surge disc brakes on the trailer. Unlike surge drum brakes, surge disc brakes are not free backing. The 5th wire energizes a solenoid near the brake cylinder on a surge disc brake system, preventing fluid from reaching and activating the calipers of the brakes.
Plugging a 5 wire plug into a 4 wire receptacle will cause no problems. What you will need to make sure of is using a 7 pin (round) to flat adapter. There the 5th plug IS energized and you would need to be sure the 5th wire on the trailer if not used is capped off properly so you don't cause a short.
Enjoy your new boat and feel free to ask anything. We're all here to help!
Yeah, my vehicle's factory installed hitch comes with a four pin flat connector. I'm thinking about building a 4 pin to 5 pin adapter and tapping into the reverse lights for the fifth pin on the adapter, as I have other trailers that use the flat four. Or maybe, I'll yank the four wire, and replace it with the 5 pin, and make a 4 pin adapter. Choices, choices.