What is an electric brake controller and why do you need one?
Wondering if you need an (ECB) Electric Brake Controller? We explain what an ECB is and why you need one when towing your RV or trailer.
By Robert Pepper,
August 10, 2023
The answer to why you need an electric brake controller is simple. Do you want the ability to both slow down and handle potentially deadly trailer sway? And, do you like your tow rig being both insured and legal?
Yes, your tow car has brakes. But those brakes are designed for the maximum mass of the vehicle, which is, let’s say, 3,000kg. Now if you tow another 3,000kg then that’s 6,000kg of mass which needs to be slowed. Your car maker definitely did not design their brakes for that sort of abuse.
The solution is to add brakes to the trailer, preferably of the electric brake controller kind. Now you don’t need to do that for light trailers, which is why every car has a maximum braked towing mass. Beyond this, the carmaker says, “You must have brakes on that trailer”.
A popular misconception is that this mass is 750kg, which is the case for medium to large 4WDs such as the Prado, Discovery and Patrol. But for smaller vehicles such as a Forester or Jimny, the maximum trailer mass for an unbraked trailer is more like 300-400kg. Beware when buying light trailers, as the salespeople are often unaware of this fact.
Overrun trailer brakes
There are two common types of trailer brakes in Australia; overrun and independent. The overrun brakes simply work when the tow car slows down and the trailer pushes into the back of the tow car. They are simple and legal for trailers up to 2,000kg GTM, which means Gross Trailer Mass. GTM is the mass on the trailer wheels, not the mass of the entire trailer. So not including the tow ball mass.
However, I’m not a fan of the overruns for trailers that exceed more than a third of the tow car weight. Why? I don’t think they offer enough control when towing in conditions like hills, high-speed freeways and definitely offroad.
Independent trailer brakes
Then there are independent electric brakes. These are operated in two ways – an automatic mode or a manual mode. Automatic mode is where the system detects when the tow car slows or brakes and then applies the brakes. Manual mode is where you can use the controller to apply the electric trailer brakes without ever touching the tow car brakes. The amount of braking force is variable too. You can see why these independent brakes offer much more control than the overrun versions, and they also offer a safety advantage as they are easy to test. As soon as you move off, manually apply the brakes and you know they work.
The independent electric brake controller systems offer other advantages too. As the amount of trailer braking for a given tow car brake is variable, you can optimise the trailer braking for the situation. For example, when backing a trailer I’d typically set the trailer brakes to zero as I find it just makes things jerky. However, offroad, I might have the tow car on a steep incline, the trailer on the flat, not be touching the tow car’s brakes and using the trailer brakes to lower the tow car down the hill.
Similarly, if I’m towing a car on a car trailer then the amount of braking I need when the trailer mass is 1,000kg is different to when it’s 2,500kg with a car on. And at high freeway speeds, I typically dial up the braking force in case of an emergency stop. This is the same for long downhills. Essentially the interplay between the amount of braking you need on the tow car vs the trailer is highly variable, and it’s good to be able to optimise both for the conditions and particular towing situation.
Trailer sway
Some electric brake controllers work off how fast the car decelerates, which may or may not be by using the brake pedal, and others just work off the brake pedal. The manual override mode is a very important feature that’s often used to combat trailer sway. If you find your trailer is dancing around behind your tow car, then simply keep straight, don’t accelerate or brake the trailer, and apply the trailer brakes independently. That should fix the sway instantly, as shown in the video below, and it’s a very important skill to develop.
Modern electric brake controllers
Newer electric brake controllers, such as the Redarc TowPro Elite, now have two modes, User and Proportional. The controller has a dial from 0 to 10, and in User Mode, sends braking force to the trailer dependent on the setting. So at 0, there’s no braking and at 10, it’s maximum. The Proportional mode detects how quickly the tow car is decelerating and sends a proportional braking force to the trailer depending on that deceleration.
Every electric brake controller is different, and it pays to understand how they work. Unfortunately, in my experience, the manual is quite technical and doesn’t explain things in context, only really making sense if you already understand things, and the sparky who installs it may not really know either. Your best bet is a professional towing course.
Some vehicles have an ITBC, or Integrated Trailer Brake Controller. This is simply an electric brake controller which is built into the car, not added aftermarket. ITBCs are common on the larger American utes such as RAMs, and now Ford has introduced them on the next-gen Everest and Ranger. See my other article for details about why that’s such a great safety innovation.
Important pieces of advice
Electric trailer brake controllers are a critical safety item, so I’m going to end with some important pieces of advice. First, know that trailer brakes may be required below a 750kg trailer mass. Second, test your brakes as soon as you pull away. Third, if you get sway, you must activate the trailer brakes only, and immediately. Finally, your electric brake controller has several modes and it is really, really worth the time to explore and understand what they do before you need it in an emergency.
