Trailer Tow Hack

[Bufordw]

I wanted to use the trailer tow odometer when towing my boat. But it didn’t work because my trailer has a 4-pin connecter and surge brakes. So, I decided to trick my truck to make it think electric brakes are connected so I could use all of the features of having a 7-pin trailer hooked up while towing my boat.

I measured 3 different RV trailers with electro and hydro/electric brakes. The impedance was ~ 3-6 ohms. I found some 5.1ohm 1/4watt resisters (1/2 watt would be better) in my hobby stash and connected it to the electric brakes and ground pins of a seven pin connector. I also, added a vehicle side 4-pin connector to hook to the trailer when towing. I needed about a foot wire more for my trailer to comfortably hook to the trailer connector on the 2019, so I made a pigtail adapter.

Before connecting the adapter you should set up your trailer to “LIGHT ELECTRIC” and the GAIN to 0.0. DO NOT INCREASE THE GAIN. You may damage the resistor.

Now all the towing features work. The Trailer Tow odometer works, The Truck now states that electric brakes are connected and rear park sense is turned off automatically when put into reverse. See the pictures….
Forgive the crappy drawing, I don't have a good schematic program.

Use at your own risk. I will not be liable for any damage.