How to Wire Up a Boat Trailer with a Reverse Light on a Vehicle with a 4-Way Connector

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Question:

I have a Sarah Unlimited 2007. I have a factory tow package on it. I want to add back up lights to my boat trailer, so when I am backing my boat down the ramp at night, I can see the ramp. My jeep and trailer are both 4 pin harness. I have been told I need to go to a 7 pin set up. Every seven pin set up looks like I have to run wires to the battery. Is that just if I had brakes on my trailer? If I dont have brakes on the trailer, is it just plug and play with the harness kit in the right rear light? What kit do I need, and what kit do I need to add to my trailer? I would like to tie into the current wires on the trailer, so if I use my wifes vehicle, we can still plug the 4 pin into her vehicle and it still work, just no backing lights. Thanks,

asked by: Joshua S

Expert Reply:

I have a solution for you, but electricity and water do not mix well so you will want to unplug the trailer wiring harness before you submerge the trailer in the water.

The best setup I can recommend that will accomplish your needs and will still allow your wife's vehicle with a 4-way to connect to the trailer would be a 5-way setup.

To convert the 4-way on your Jeep to a 5-way all you will need is the # 20036. Basically this will plug into the 4-way of your Jeep and the extra wire will get run to the reverse light circuit of the vehicle.

For your trailer you will want to cut off the 4-way that is on it currently and wire in a # A40W5B in it's place. Basically you will cut all of the wires but the blue one to a short length so that they can be connected to your trailer wiring. The blue wire will be left long and will get run to a reverse light. I would recommend the # BU70CB as a back up light since it is designed to be submerged under water (with the wiring harness disconnected like I previously mentioned.)

Your wife's 4-way connector will plug right into the 5-way. The extra pin will just overhang the rest of the connector.