Originally Posted by 1builder
so i know how the trailer can take the electrical signal and turn it into braking power but how does the controler tell it how much to push and how does it get to the trailer? is it a seperate set of wires in the adapter harness for the trailer lights? new to towing and kinda confused.
The power is controlled by what you have to brake controller set to output, when the brake light is on...
There are (3) main kinds of controller
1. Cheap ($65) - On/off controller. Puts out a set voltage (that you set via a slider or dial) to the trailer brakes when the brake lights are on.
2. Accelerometer-based (Prodigy $90, P3 $120) - Have an accelerometer inside them that, (only) when the brake lights are on, varies the brake voltage to the trailer brakes by how fast you're stopping the vehicle.
3. Pressure-based (~$400 - $500) - These actually tap into the brake lines of your vehicle, and have a pressure sensor that supplies a given amount of braking voltage to the trailer brakes, compared to how much pressure is in the lines of the tow vehicle's brakes.
#1 will get you by
#3 is the best, but is $$$
#2 is 98% as good as #3 and the last one I got brand new with warranty off of eBay was $112 shipped
Go Tekonsha P3, if you're buying... I have a thread in this section on how to install it, with pictures.