Troubleshooting Trailer Wiring on 2012 Ford Expedition

Updated 05/03/2019 | Published 05/02/2019

Products Featured in This Question

Adapter 4-Pole to 7-Pole and 4-Pole

(660)

$61.90

10 Gauge Wire - Blue Primary - Per Foot

(104)

$1.74

ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit

(522)

$192.77

Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

(704)

$36.63

Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

(184)

$17.94

Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 7-Way and 4-Pole Flat Connectors

(721)

$36.96

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3401)

$101.73

Hook Probe Circuit Tester

(62)

$13.33

Question:

Bypass factory towing package and power trailer brake and turn lights off of 2012 Ford Expedition brake and turn lights?

asked by: Allen F

Helpful Expert Reply:

Your 2012 Ford Expedition should have a factory 7-way harness. There is a round connector called a US CAR connector that will allow you to have the wiring functions you need. If you need a 4-way, use # C55515 or if you want to add a 4-way in addition to your 7-way you can use # C55384. If you want a replacement 7-way use # C55774 which will give you both options.

If you are having issues with function, check your owners manual for fuse or relay issues if it is just a single function not working. There are many different fuses and relays to check on your vehicle.

If your fuses and relays are good I recommend checking your wiring at the round US Car Connector. The pin locations will match the 7-way I've attached for reference. You can use a circuit tester like # PTW2993 to test each function. If they work, then simply add a new harness like listed above. If not, then you can choose to tap into your factory wiring at the tail lights using a harness like the ZCI Circuit Protected Vehicle Wiring Harness with Installation Kit # 119250KIT which will protect your vehicle wiring. This will give you the 4-way trailer connector then you need the 7-way, you can use # ETBC7 which will help you with the additional wiring functions and is a complete kit.

If you have the factory 4 way and simply want to add the other functions, you will need the # 37185 and then you will tap into the factory 12V power and brake controller output wires found along the rear frame rail using # 10-1-1 sold by the foot.