Recommended 4-Flat to 5-Way Adapter

Updated 12/08/2025 | Published 11/13/2025

Products Featured in This Question

Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End

(103)

$12.90

Hook Probe Circuit Tester

(60)

$12.41

Question:

HI, My car has a four wire connector but my trailer has a five wire connector it has brakes. Is there an adapter I can buy or does the car connector need to rewired?

asked by: John

Expert Reply:

There sure is John. You're going to need the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat item # C57187. This adapter is going to plug directly into your car's 4-flat. The additional wire will need to be spliced into your car's reverse circuit.

You will need to use a circuit tester like item # PTW2993 to locate your car's reverse circuit. Unfortunately, we do not know the exact location or color of the reverse light circuit wire. I've linked an installation video below that will walk you through the steps of getting this adapter installed and where to look for the reverse circuit on your car.

A setup like item # C57187 is going to be used on trailer's with a surge braking system. What kind of trailer do you have?

You can add this information and any other questions you have where it says Reply to Jerred H and I'll be happy to answer them.

expert reply by: Jerred H

Trailer Connector Adapter
(click to enlarge)

Jerred H.

12/8/2025

Hey John, how did things go with the Curt 4-way to 5-way adapter and finding your reverse circuit? Your update could make it easier for others wiring a similar trailer setup.