Originally Posted by Lincoln
Some have mentioned losing signal strength covering that distance.
I would indeed be concerned about that. It's a small wire and a long run, and that equates to poor current carrying ability. The wiring diagrams call it a "US GEAR INTERFACE" and as such it is meant for use with a US Gear Unified Tow Brake. That is a system for toads that uses a small control panel in the MH cab, and a controller in the toad. The signal between them (the wire normally used for controlling electric brakes) is a low current data signal, so the smaller wire works well for that use.
However, when using a regular electric trailer brake controller, that wire between the controller and the trailer is a high current signal that actually provides power to the trailer brake magnets. In a car/SUV/pickup, that wire is usually much bigger than what Monaco uses in the US Gear pre-wire. With the wire extra length involved, it should be even bigger still.
Hoping that woks otherwise I'll have to install a wire and relay at the back.
I don't think the relay is going to cut it. That output from the brake controller is a varying voltage/current depending on braking effort and the controller settings. A relay is a straight on/off device. If you trigger the relay from the brake controller output, and use it to switch 12V to the trailer brake magnets, you won't get the smooth operation you need. Instead, under light braking you won't get any trailer braking because the relay won't activate. Then, as the braking effort increases, the voltage to the relay coil will increase until it finally pulls in, and at that point you will have full power to the trailer brakes locking them up.
If you want to properly control electric trailer brakes, I think you only have two options:
- Use a controller that mounts back at the trailer plug, like the Wireless Prodigy
- Run a new heavy gauge wire from the controller to the trailer socket.
10 gauge wire is fairly common in trucks/SUVs for the controller output wire. For the extra length involved with a motorhome, I would think you'd want to go bigger.