Brakes
Electric brake controllers: which type you need, and the rules
Electric trailer brakes do nothing on their own: a controller in the tow vehicle tells them how hard to brake. Here is which kind suits which trailer, what the rules require, and what we plan to stock.
Hitch & HighwayChecked 3 October 20262 min read
Quick answer
For a caravan, choose a proportional controller: it senses how hard the vehicle is braking and matches the trailer's brakes to it. Time-based controllers ramp up over a set time and are cheaper but less smooth. Under-dash and wireless (in-trailer) types do the same job. Trailers over 750 kg need brakes, and electric brakes must be controlled from the tow vehicle.
Which type?
| Type | How it brakes the trailer | Suits |
|---|---|---|
| Proportional (inertia) | Senses the vehicle's deceleration and applies matching force | Caravans and heavier trailers; smoothest |
| Time-based (delay) | Ramps up to a set level over a set time when you brake | Lighter trailers, occasional towing |
| Wireless or in-trailer | A module in the trailer, adjusted from a phone or remote | Swapping between vehicles; tidy installs |
All of them have a manual override, so you can apply the trailer brakes alone to settle sway.
What the rules require
Under Vehicle Standards Bulletin 1, trailers over 750 kg gross trailer mass must have brakes, and except for over-run (override) brakes, the braking must be "activated by a control signal generated by the tow vehicle". Over 2,000 kg, the brakes must work on all wheels and the trailer needs a breakaway system. See electric trailer brakes for the full rules.
Installation
A controller needs a heavy-gauge feed from the battery with a circuit breaker, an earth, a stop-light signal, and an output to pin 5 (blue) of the trailer socket. On modern vehicles the wiring often runs through a vehicle-specific harness. An auto electrician is the safe choice; set the gain with the loaded trailer on a quiet road.
Planned range
When we open, we plan to stock proportional under-dash and wireless controllers, wiring kits and breakaway kits. No prices or stock yet.
Common questions
How does an electric brake controller work?
It sends a variable signal from the tow vehicle to the trailer's electric brakes when you brake, so the trailer slows itself instead of pushing the vehicle. Proportional controllers match the signal to how hard you are braking.
Can I tow a trailer with electric brakes without a brake controller?
No. Electric brakes need a control signal from the tow vehicle, which is what the controller provides. Vehicle Standards Bulletin 1 requires non-override trailer brakes to be activated by a signal from the tow vehicle.
Can you install an electric brake controller yourself?
It is possible with auto-electrical skills, but it involves a battery feed, circuit protection and trailer socket wiring. Most people use an auto electrician.
Do I need a brake controller if I have a 7 pin trailer plug?
The 7-pin plug carries the brake signal on pin 5, but something has to generate it. Without a controller, pin 5 does nothing.
Sources
Hitch & Highway is a towing and van gear store in preparation and is not trading yet.