Installing a 7-Way Trailer Connector on a 2011 Mercury Mariner

Question:

I am looking on where I connect my other wires to a 2011 mercury mariner because I am hooking up a wiring adapter for a 4 prong to 7 prong. I have the 4 prong installed and need the 7 for the pop up trailer that has electric brakes.

asked by: Daniel

Expert Reply:

On the Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector, # 30717, the white wire grounds to the vehicle frame, the black wire will connect to the positive terminal on the vehicle battery via a 40 amp circuit breaker, # PK54540, the blue wire will connect to the blue wire on a brake controller, and the yellow wire can be attached to the reverse light circuit.

If the trailer does not have reverse lights but does have accessories on it that require additional 12 volt power that are not connected to the main 12 volt pin, the yellow wire can also be used as a 12 volt accessory wire which would require being attached to a separate 40 amp circuit breaker and then to the positive battery terminal. If not needed, it can be taped up and stowed out of the way.

Since the trailer has electric brakes, you will need a brake controller to make them work. I recommend the Tekonsha P2, # 90885. It is one of our most popular brake controllers because it is easy to set up and easy to use.

To help with installation, I have included links to an FAQ article and a video that should help when making the blue and black wire connections and when installing a brake controller. The duplex wire they use is a 25-foot length of # 10-2-1, which is needed to reach the front of the vehicle from the 7-Way. The only other part needed is a circuit tester like # PTW2993 if needed.