I am building a tester for my trucks and trailers. It's easy to test the lights, but testing the brakes controller is difficult without hooking it up to a trailer. Is there anyway to fool the controller into thinking that it is hooked up? I.E. hooking it up to a resistor of some kind?

Thanks for the help.

In DC circuits, a magnet coil is equal to simple resistance. Measure the resistance of a brake magnet. Then get a resistor to match it. Be aware that a resistor converts electricity to heat. As long as you're only trying fool the brake controller into thinking its connected to a magnet, you'll be okay. The heat problem will be apparent when you try to test the controller's output. Then things will get HOT.

Thank you very much for the information. What I am trying to do is fool the controller so it will in effect "turn on" so I can measure voltage with a VOM. However, what it sounds like is if I plug a resistor in line so I can test its output, then I have created a new problem. Maybe the best option is to get a magnet out of a brake and test the voltage that goes to it.

Thank you again.

A single magnet may or may not be the solution for your tester. If you have brakes on four wheels, you'll have four brake magnets wired in parallel. Similar for just brakes on two wheels or a single axle... Two magnets.

The total resistance for identical magnets is = resistance of one magnet / number of magnets.

Another point. Heat in resistors is not a bad thing IF the resistor can handle the amount and temperatures. For instance... an ordinary 60 watt light bulb has a resistance of about 8 ohms. So it can safely dissipate 60 watts up to 120 volts.