Adding a 7-Way Round Pin Trailer Connector to a 2010 Ford Expedition with a Factory 4-Way Flat

Question:

Is there a item like 37185 that has round pins that would fit a 2010 Ford Expedition with factory flat 4 trailer tow package because the trailer I need to tow has round pins

asked by: John

Expert Reply:

Vehicles manufactured now-a-days are fitted with the blade style 7-Way so that is what most manufacturers make to fit vehicles either as replacements or aftermarket add-ons. To add a 7-Way round pin to your 2010 Ford Expedition you will need # PK11720, boot # PK11761, and mounting bracket # PK11771.

What you can do is use # 37185 and replace the 7-Way blade with the 7-Way round but cutting the wires and reattaching them to the 7-Way round. But the easiest thing to do is go ahead and install the # 37185 and then use an adapter, # 47595. This will allow you to tow the trailer with the round pins while still keeping the more popular 7-Way blade style.

To install # 37185 you will plug in your 4-Way to it then ground the white wire to the vehicle frame. The remaining 3 wires will need to be hardwired in. If you follow your factory wiring harness forward on the vehicle it should plug into another connector. Forward of this connection point, if you pull back the protective covering, there should be additional wires to hardwire into for the remaining functions on the 37185.

Use a circuit tester like # PTW2979 if you do not already have one to test the wires. One wire should be 12 volt power, one will be reverse lights, and one will be output from a brake controller.

If you need to add a brake controller to control the electric brakes on the trailer (if equipped) then I recommend # 90885, because it is easy to set up and easy to use. To wire in the brake controller, the white wire will ground to the negative battery terminal, black connects to positive battery terminal via a 20 amp (2 to 4 brakes # PK54520) or 30 amp (6 to 8 brakes # PK54530) circuit breaker. Red connects to cold side of the brake switch, and blue will go back to the blue wire on # 37185. I have linked an FAQ that should help.

A third option is to replace the trailer connector on the trailer with a 7-Way blade style using # H20046. This will allow you to keep the connector on the tow vehicle, not use an adapter, and the trailer will then be fitted with the more widely used blade style. If you go this route you do not want to wire things by color. Use the wiring code on the product page and wire by function.