How Brake Controllers Work

Although there are several different styles, we can divide brake controllers into two distinct groups -- proportional brake controllers and time delayed brake controllers.

Proportional brake controllers use a motion-sensing device to detect how fast the tow vehicle is stopping. The moment the driver applies the brakes, the brake controller applies the same amount of braking power to the trailer's brakes -- if the truck is stopping quickly, the trailer will stop quickly; if the truck stops slowly, the trailer will stop slowly. In a situation that requires heavy braking, for instance, a proportional brake controller will cause the trailer to stop at exactly the same time as the truck does. This type of brake controller provides the smoothest braking, and because both systems are doing the same amount of work, it reduces the amount of wear on each vehicle's braking system.

Proportional brake controllers are also known as pendulum brake controllers because of the way they sense motion. These devices use the position of a pendulum as a motion-sensing device, and drivers typically need to calibrate them before using them. When the vehicle is on a level plane and the pendulum is pointing straight down to the ground, the brake controller doesn't sense any motion and won't send any signals to the trailer's brakes. When the vehicle moves, however, the pendulum points toward the rear of the vehicle. As soon as the vehicle brakes, the pendulum swings forward. Depending on how far the pendulum swings, the brake controller sends a degree of power to the trailer's brakes.

Time delayed brake controllers, on the other hand, provide a pre-determined amount of power to the trailer's brakes when the truck stops. The power is set beforehand by the driver and depends on how much trailer weight he's towing. A delay will always occur when the brakes are pressed; however, a sync switch allows the driver to adjust the length of the delay. Time delayed brake controllers put more wear on braking systems, but they're less expensive and easier to install than proportional brake controllers.

Sometimes simply hooking up a brake controller to your trailer isn't enough reassurance. It helps to know how much brake power you're applying during a stop or whether the trailer brakes are even functioning at all. Brake controllers almost always have some type of monitor built in, which, if placed correctly -- often under the instrument panel, near the driver's right leg -- is easily viewable from the driver's seat.

Digital display screens show the voltage delivery going from the brake controller to the trailer's brakes. The more you press down on the brake pedal, the more power will go toward the trailer's brakes; if you give the pedal a softer touch, less power goes to the trailer's brakes. The brake controller monitor reflects the amount of pressure and power you're applying to the brakes. Brake controller monitors help you make sure your trailer is properly connected and will notify you of any electrical problems that could put you in danger.

As technology improves, newer brake controllers, specifically electronic ones, offer more monitoring options. Some models come with LCD screens that give specific, continuous diagnostics and important warning signals to drivers. Often, displays are customizable, with language options in not just English but French and Spanish -- some even offer color choices.

Installing a brake controller is a fairly easy task. The first step involves simply mounting the brake controller in an area that is easy to access. Most people choose to place it under the dashboard and directly above your right leg; this keeps the brake controller in view, where you can monitor any potential problems.

Brake controllers typically come with a four-wire configuration, which can be hooked up to the braking system's wiring. The four separate connections are:

If you're not comfortable with bundles of wires, you might want to have a trained professional take care of your brake controller installation; however, if you know what you're doing and follow the directions provided by the device's manufacturer, installing a brake controller shouldn't be a problem.

For lots more information on braking systems and towing, see the next page.