Converting 7-Pole on 2018 Mack Dump Truck to 6-Pole for Trailer

Updated 08/31/2017 | Published 08/30/2017

Products Featured in This Question

Curt Tail Light Converter with 4-Way Flat Trailer Connector

(367)

$29.31

Hook Probe Circuit Tester

(66)

$14.36

Question:

Hello I just purchased a 2018 Mack granite dump truck and it came wired from the factory with the 7 pole pin electrical connection and my trailer is a 6 pole pin so I purchased the hm47445 adapter and the only thing that works is the turn signals and the 4 way flashers, is this the right adapter or do I need something else? Thank you

asked by: Kevin W

Helpful Expert Reply:

What you will need to do is plug the Hopkins Trailer Connector Adapter # HM47445 into the 7-Pole on your 2018 Mack and test each pin with a Circuit Tester # PTW2993 so that you can map out what the functions should be.

You will then want to use a 12V power source, like a typical vehicle battery, and test the 6 pins on your trailer. You can then swap any wiring on your trailer connector if need be.

If the trailer that you are pulling has the standard trailer side 6-Way setup like the picture I attached (keep in mind that sometimes the 12V Power and Brake Controller pins are swapped), and your Mack is wired for a Commercial 7-Pole, like the vehicle side picture I attached, then you will definitely need to do some rewiring. The 6-Way has the Turn Signals combined with the Stop signal for the trailer whereas your commercial setup on your Mack has the Hazard Lights combined with the Turn Signals but the Stop signal is on a separate pin.

What I recommend doing is using the Universal Upgraded Tail Light Converter with 4-Pole Flat Trailer Connector # C56175 to tap into the Right Turn, Stop, Left Turn, Tail Light, and Ground wiring on your Mack. This converter will combine functions to give you a 4-Pole connector that has Right Turn/Stop, Left Turn/Stop, Tail Light, and Ground.

You can then use the Mighty Cord Adapter 4 Pole to 6 Pole # A10-6034VP for the light functions on your trailer to work properly. You will just need to ground the ring terminal to your tow vehicle frame and then if you need the 12V Power and the Brake Controller functions you will need to run wiring to the Black and Blue wires respectively.

I have attached some pictures, review videos, and a helpful article on wiring that you can use to help with this install.