Controlling your Brakes

Stuart Grant — 18 July 2011

INSTALLING ELECTRIC BRAKES to your tow vehicle is a job best left to experts. Trailer and caravan brakes are not something you want to leave to chance: discovering they don’t work properly until it’s too late is not an option.

Electric brake control units are sophisticated pieces of equipment and fitting them correctly is essential to your safety, as well as that of your passengers and other vehicles. When I was recently given an opportunity to test a Vista RV Crossover offroad camper, I found I needed to get a brake control unit fitted to my Mitsubishi Pajero tow vehicle.


According to the Australian Design Rules, trailer brakes are required for any trailer, except single-axle trailers weighing 750kg or less. Trailer brakes are required on at least one axle when the trailer weight is less than 2000kg, while brakes must be fitted on all axles if the weight is greater than that. Given the Vista RV Crossover weighs in at 1100kg, I thought it best to seek the advice of professionals. In this case, ADP Caravan Services in Kilsyth, Vic.

ADP’s workshop manager, Gary Lacey, gave me the low down on electric brakes as he installed a Hayman Reese Guardian IQ unit to my rig. “It’s important that the right gauge wiring is used to make sure sufficient current can be fed to the trailer brakes. This helps to make sure they work effectively and at the correct rate.”

Electric brake control units, like the Hayman Reese Guardian IQ Gary recommended for my Pajero, typically feature a control unit mounted within reach of the driver’s seat. This can be manually adjusted to apply the correct amount of braking force for a given situation, like when a van is swaying, for example.

Some units (including the Guardian IQ) have a boost system where the braking force can be dialled up if you find yourself in a situation where greater than normal braking pressure is required, such as on very long or steep descents.


A brake controller is an aftermarket component that provides the activation of, and power for, electric trailer brakes. There are a few different types, but the main component of a brake controller kit is a small rectangular box commonly fitted to a metal bracket on the lower steering column panel, or leading edge of the lower dash, of the tow vehicle.

The controller is powered by the vehicle’s battery and is activated when the foot brake in the tow vehicle is pressed. The brake controller is wired into the vehicle’s brake light switch circuit, so when the switch gets power to turn on the brake lights, it also activates the brake controller.

The controller is the brain behind the activation of the trailer brakes. When the brake light switch is activated, the controller feeds a current through the trailer plug to the caravan brakes. The controller does not interfere with the tow vehicle’s braking system.

How long an electric controller delays activating the caravan brakes, and how much force it signals the caravan brakes to apply, depends on the design of the controller.

There are a few different options, but one of the most popular systems features an interior pendulum that senses deceleration and, based on the amount of braking force applied, can vary the force on the caravan brakes. – Philip Lord.


brake control brake controllers brakes braking towing tech RV tech trailer brakes Tech & Towing Equipment Adventure 2011


Stuart Grant