Need Adapter For Tow Vehicle With 5-Flat And Trailer With 7-Way

Updated 09/17/2025 | Published 09/07/2025

Question:

I have a 5 pin flat coming out of my tow vehicle. My boat trailer soon to be my trailer has the 7 pin. The trailer has surge brakes. 1: is there a 5 pin to 7 pin adapter? 2: if not, to get the boat and trailer home 300 miles and to back up, which pin in the 7 pin is the backup light pin? Knowing which wire to tap there should be two unused would simplify my cutting and splicing to convert the trailer to a 5 pin.

asked by: Tom H

Expert Reply:

Hey Tom, thanks for reaching out. Yes, we do have an adapter that can work for this. Take a look at the following:

- Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat # C57672

You just need to find a spot to mount the 7-way bracket. You can then plug the 4-flat end into the 5-flat on your vehicle. Then plug your trailer into the 7-way for your lights. The yellow wire on the adapter is for reverse lights. On a typical 5-flat, the blue wire would be for reverse lights, but wire color is not always universal, so I do recommend testing for function.

Alternatively, like you said, you could just wire a 5-flat onto the trailer but you will be doing a bit of wiring either way. The 7-way is way more common compared to the 5-flat so I am thinking adding the 7-way to your vehicle is the way to go.

What is your tow vehicle by the way?

expert reply by: Jesse M

Curt Trailer Connector Adapter C57672
(click to enlarge)

Tom H.

9/16/2025

Got it, thanks. I have a 25 hyundai palisade, 5000 tow rating. The adapter 57672 looks to make the reverse wire an orphan. Sure would prefer a 5 pin to 7 pin. Thanks for getting back to me, Tom

Jesse M.

9/17/2025

@TomH The 5-pin is not very common these days so we would not have an adapter specifically for a 5-flat to a 7-way. The # C57672 would be our best option for doing what you are needing to do.