How To Wire 2008 Subaru Outback w/ Existing 4-Way To Tow a Pop-Up Camper w/ 7-Way Connector

Question:

Ive recently purchased a popup trailer with a 7-pin connector. My 2008 Subaru Outback has a 4-pin connector. Ive wired up an adapter from a Pollack 12-705 receptacle and a 4-pin plug this works perfectly to control the tail lights, brake lights, and turn signals. Now Id like to add 12-volt power to the battery charging circuit on the trailer. I read your answer to a previous question http://www.etrailer.com/question-4316.html, but Im wondering if I could wire up a connection to the cigarette lighter plug in the back of the Subaru rather than running wire all the way up to the battery. Is this a reasonable idea? Would I still need a separate circuit breaker? If the idea is good, how would you suggest wiring the connector that plugs into the cigarette lighter plug? I assume the hot wire would be connected to the black terminal in the 7-pin adapter. Thanks for any comments!

asked by: Doug

Expert Reply:

To connect your 2008 Subaru Outback that has a 4-way connector, to your pop-up trailer that has a 7-way connector, you will need to install the Adapter 4 Pole to 7 Pole, part # 37185. This will give you a 7-way at the rear of your vehicle.

To install part # 37185 on the rear of your Subaru Outback, you would begin by plugging your existing 4-way to the 4-way of part # 37185. Then, you will connect the remaining wires. The White wire is ground and should be connected to a clean metal surface. Black is 12 volt power and should be connected to the positive battery terminal via a 40 amp circuit breaker, part # 9510. The Blue wire would connect to the Blue wire on the brake controller if your pop-up trailer has brakes. The Purple wire is the reverse light circuit, if your trailer does not have reverse lights, you can tape this wire off and tie it out of the way.

It is not recommended to run the 12 volt wire to the cigarette lighter plug. This is not a safe way of wiring a power wire, and would require a direct 12 volt connection.

I have linked an FAQ on wiring and a video installation of the Adapter 4 Pole to 7 Pole, part # 37185, on a different vehicle, that you can use as a reference.