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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Mercury
Satisfied Customers: 6576
Experience:  ASE Master Certified. ASE Gasoline Engine Performance Certified,Ford Senior Master Technician
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We have a 2010 mercury mountaineer that we need to wire the

Customer Question

we have a 2010 mercury mountaineer that we need to wire the trailer power/ brake/ lights plug to and want to know where the plug is located to pick up power for the trailer plug at and how to identify it
Submitted: 6 months ago.
Category: Mercury
Expert:  A. Penland replied 6 months ago.

What trailer harness kit are you installing?

Customer: replied 6 months ago.
I am not using a kit. I bought the electrical connector some years ago and need to know where to pick up the wires for the brake and hot wire from the battery. I have checked and the wiring is there for the brake controller and fuses. The original wiring to the back of the vehicle only had the lights only.
Expert:  A. Penland replied 6 months ago.

Can you give me the VIN#?

Customer: replied 6 months ago.
Expert:  A. Penland replied 6 months ago.

Below is the wiring diagram for the 4 pin trailer tow system. There should be a connector in the right rear of the vehicle underneath behind the bumper just after the rear tire. Below is what the connector looks like.

Customer: replied 6 months ago.
I don't know if you misunderstood me. I need to know if you can tell me where I can connect to the +12 volts and the brake voltage for the trailer as the only wires I see are the four light wires
Expert:  A. Penland replied 6 months ago.

Do you have that connector I posted in the right rear corner of the vehicle between the rear bumper and the right rear tire?

Customer: replied 6 months ago.
I see the connector but I only see four wires. The wiring harness comes from the front of the vehicle and splits( no plug) going out to the two plugs for the tail lights. about half way across the vehicle is the split with the four wires to the trailer plug.
Expert:  A. Penland replied 6 months ago.

That is where you tap into the vehicles harness safely without shorting out modules. If you were installing a Ford trailer tow harness kit, it would connect there also.

The small numbers near the wires, 5,6 and 7 and the pins in that connector. Splice your trailer harness into those 4 wires and the white wire in your harness should be ground.

Customer: replied 6 months ago.
FYI the wire for the brake and the power to the trailer were not at the back of the vehicle. After tracing it back I found the plug with the two wires I needed behind the right front tire. Sorry you missed this one
Expert:  A. Penland replied 6 months ago.

Thank you for the update.