How to Wire Pop-Up Trailer so Battery is Maintained Through Trailer Connector

Question:

I have a 2017 Subaru Outback and am towing a popup camper trailer. I purchased the 7-pin brake controller kit from you, which is attached to the vehicle battery by a 20 gauge wire. I assumed I could connect a wire from the trailer 7-pin to the positive terminal on the trailer battery and Id be all set. However, the trailer 7 pin is sealed. Would I have to spice into the wire tubing to make the connection?

asked by: Michael D

Expert Reply:

Somewhere further downstream of the point where the trailer connector wire on the trailer side meet, you should be able to access all the individual circuits where they branch off and tap in to the power feed for the battery. If that's not possible, your best bet would be to remove the existing plug and part of the cable along the trailer tongue and wiring in a new cable/plug/junction box like # HS381-9000 which would be installed as shown in the video I've linked for you. The junction box provides a clean way to make all the connections between the trailer connector and the various wiring connections on the trailer while keeping them protected from the environment. Keep in mind that the color coding of the trailer plug/harness included in this kit might be color coded differently than the way your trailer is wired now, so be sure to look at the color code provided on the linked product description page for the # HS381-9000.

In the junction box, you can make the connection to the 12v power feed from the tow vehicle, but keep in mind that the tow vehicle will only be able to provide enough amperage to maintain the battery, not charge it once it's depleted. I'll link you to a help article that will explain this further.

expert reply by: Mike L