Ford Focus Trailer Wiring | etrailer Trailer Wiring Harness Installation - 2009 Ford Focus. Today on our 2009 Ford Focus, we will be installing the Tow Ready T-One Vehicle Wiring Harness with 4-pole flat trailer connector, part number 118457. All right, first thing we need to do on our Ford Focus to install the wiring harness Ford Focus Trailer Wire Harness and Connector - Best Order Ford Focus Trailer Wire Harness and Connector online today. Free Same Day Store Pickup. Check out free battery charging and engine diagnostic testing while you are in store.