How to Add a 5-Way Connector to a Vehicle That Only Has a 4-Way Connector

Updated 10/27/2025 | Published 03/01/2025

Products Featured in This Question

Hook Probe Circuit Tester

(60)

$12.41

No-Drill Mount Bracket, Long

(682)

$19.75

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

(103)

$17.00

Curt Mounting Bracket for 5-Way Flat Trailer Connector

(21)

$7.40

Question:

Hello, need help converting existing 4-plug trailer hitch to 5-plug for surge brakes on boat trailer. 2019 Toyota sienna. How do I connect the reverse light wire? Thanks!!

asked by: Rob

Expert Reply:

Hey Rob! To add a 5-way connector to your Sienna you'll need the Curt Trailer Connector Adapter item # C57187. The blue wire will be spliced into the reverse light circuit.

The easiest place to find the reverse light circuit is the wire loom that goes from the hatch to the body of the vehicle. It can typically be found near the top. Once you find this you will need to pull out the wires and test them using a circuit tester like item # PTW2993 until you find the circuit that is only active when in reverse.

I have linked a video we made installing one of these on a different vehicle. It'll walk you through the entire process. If you have any additional questions feel free to throw them into the comment box below.

I recommend using the No-Drill Mount Bracket item # 18136 and the item # C58303 to secure the 4-way connector to your hitch. This will put it in an easy to reach spot and prevent the risk of it falling onto the road.

expert reply by: Jerred H

Jerred H.

10/27/2025

Hey Rob, how did things go adding the 5-way connector and finding the reverse light wire on your Sienna? Your update could make it easier for the next person wiring surge brakes on a boat trailer.