How to Install a Towing Brake Controller: Step-by-step Guide

A trailer brake controller allows you greater control when you are towing a vehicle. Relying on your car's brake pedal can cause trailers to skid as your tow vehicle will slow at a different rate.

By using a trailer brake controller you can stop your vehicle more quickly by reducing the stopping distance. They are a necessary tool when towing either large or small vehicles and will give you peace of mind as they will prevent accidents caused by braking.

What is a Trailer Brake Controller?

A brake controller regulates the electric brakes of a trailer and allows the driver to monitor and control the trailer brakes from the cab.

They typically have different controls, including an interface which lets the driver control the brake output and allows for manual activation.

Do I Need a Trailer Brake Controller?

If your tow vehicle weighs between 751kg to 2000kg, you'll need braking on both wheels on one axle. Anything above this up to 4500kg and braking is required on all the wheels of your trailer.

Any trailer designed to accommodate these weights will have electric trailer brakes built in but without a trailer brake controller in your cab, you'll have no control over the brakes, endangering you and other drivers around you.

Some trailers come with built-in 'surge brakes, a hydraulic braking system which uses the trailer's momentum to switch on.

They don't require being wired up to your vehicle's brakes, so they are the only circumstance where you won't require a trailer brake controller.

How Does a Trailer Brake Controller Work?

Any electric brake controller operates using two different principles: time delay and proportional. Both of these apply adequate control over the braking, though a proportional operation system provides smoother stopping and greater control.

Time Delay

When the driver applies the brake pedal, a time delay brake controller will apply 'gain', gradual braking power to the trailer brakes. The gain of a time delay brake controller can be controlled on the interface to cater for trailers of varying sizes.

Proportional

This trailer brake controller uses an accelerometer to detect speed changes. When the driver uses the brake pedal, the brake controller detects the change in momentum and applies proportionate braking power to the trailer.

This system allows for more accurate control over a variety of driving scenarios, such as driving up a hill.

How to Install a Trailer Brake Controller

Towing brake controller installation is a straightforward task and can be done cheaply without having to pay a mechanic.

There are two kinds of electric brake controllers, ones with a plug-and-play function and with splice-in wiring. We'll cover both today, going over plug-and-play brake controller installation first.

There are five primary steps to trailer brake installation and wiring it up to your vehicle which we'll now explain in detail.

For this task you will need the following tools:

• A connector
• Screws
• Screwdriver

Step 1: Disconnect the negative battery

Whenever you're performing work on your vehicle's electrical systems it's important to first disconnect the battery to avoid damage to the vehicle or injury to yourself.

For this stage, you simply need to unbolt the negative battery cable and place it out of the way.

Step 2: Decide where to install your controller

The location where you install your trailer brake controller depends on your vehicle.

You can mount the brake controller under the desk or above the dash, though in SUVs or large trucks the best place is below and to the side of the steering column.

Ensure the electric brake controller is at a safe distance from any RF transmitter or CB radio you have in your vehicle to avoid the controller disrupting their electronics.

Step 3: Drill mounting holes

Once you've decided where your electric brake controller will go, you'll need to mount it. Use the mounting holes on the mounting bracket as your guide for where you'll be drilling.

When you're drilling holes for your mount be extra careful not to damage the electronics behind the panel if possible remove the panel for easy access and to avoid any damage.

Insert your screws into the mounting holes, tightening them with a wrench. Your electric brake controller may come with self-tapping screws.

Be sure not to tighten the screws too much to avoid stripping out the holes you've drilled.

Step 4: Fasten the electric brake controller into place

Once you've drilled the holes and positioned the self-tapping screws, attach the device using the bolts using the included bolts. If you've removed the panel at this point you can reattach it.

Step 5: Plug the brake controller in

It's now time to plug your electric brake controller into your vehicle's electrics. Connect the wiring to the screw terminals on your device.

One end will connect to the vehicle's factory harness beneath the dashboard and the other connects to the brake controller.

The location of the wiring harness will vary depending on the make and model of your car. Each kind of wiring is denoted by the letter B and then a number, refer to the list below and your owner's manual to see where the wiring is located in your vehicle.

• BH1 - Underneath the dash, to the left of the steering column, near the emergency brake pedal
• BH2 - Underneath dash, by the center console
• BH3 - Underneath dash, in junction box left of the steering column
• BH4 - Behind the storage pocket, above the ashtray
• BH5 - Underneath the dash, behind the center access panel on the passenger side
• BH6 - Underneath dash, near the brake pedal
• BH7 - Behind the storage pocket in the center of the dash
• BH8 - Underneath dash, to right of the emergency brake pedal

Splice-in Brake Controller Installation

Your vehicle may not have a factory connector you can use to connect your brake controller. If so you'll need to splice it to your brake output wiring. Luckily this electric brake controller installation is no more complicated than using a factory connector.

Step 1: Disconnect the battery

As before, it's important to disconnect the power supply before performing any work on your vehicle's wiring system.

This is both to prevent any harm to yourself and damage to the electrics. Disconnect the negative cable from the vehicle battery and place it out of the way.

Step 2: Locate the brake wiring

If it doesn't have a built-in factory connector, your vehicle will still have blunt-cut controller wiring for the brakes. You'll find this bundle of wires somewhere under the dash.

Handle the bundle carefully as you separate the wires and remove the adhesive holding them together.

Step 3: Identify the wiring

Brake controllers connect to the brake light switch, so it's essential to understand brake controller wiring. This will supply power to your brake controller when you press the brake pedal and is a vital step in the process.

There will be four wires in total, each with different wire colors denoting their purpose, these are as follows:

• Blue wire - Brake output
• Red wire - 12+ volt
• White wire - Ground
• White wire with blue stripe - Stop lights

Step 4: Splice the corresponding wires

You'll need a splice for this stage to connect the wires and will need to strip them if necessary. Match the wires as follows:

1 - Connect the blue vehicle wire to the corresponding blue brake controller wire

2 - Connect the red 12+ volt wire to the black brake controller wire.

3 - Connect the white ground wire to the white brake control wire.

4 - Connect the white and blue striped wire to the red brake control wire.

Step 5: Mount your brake controller

When the wires are connected securely using a splice you can plug them into the vehicle's brake controller unit.

Decide where to mount your brake controller, using the mounting bracket as a guideline for where you'll need to drill into your dash. Make sure you're positioning your electric brake controller somewhere it is easily visible and accessible but not in the way of your vehicle's dash.

You can remove the panel at this point to avoid doing any damage to the electrics while you drill.

Most brake controllers come with self-tapping screws to attach the mount once you've drilled the holes, then use bolts to attach the brake controller to the mount.

Step 6: Connect the power wire to battery

Once you've wired and mounted your brake controller, the final step is supplying power to it. You will do this with the factory power feed installed in your vehicle which you'll find under the hood by the fuse box. Attach this cable to the auxiliary power input in your vehicle's fuse box.

Once this is complete you can attach the negative connection to your vehicle battery.

How to Test an Electric Brake Controller

To test your trailer connection you will need a multimeter.

A trailer will usually have two brakes, one for each axle. As we discussed earlier, any trailer weight between 751-2000kg will require the brakes on the axle, anything in excess of this up to 4500kg needs braking on both axles.

You'll need to know the size of your trailer brakes and how many your trailer has when testing the connection.

You'll need a basic knowledge of a 7-pin trailer plug and a fully charged 12-volt battery to test the connection.

Connect the blue wire to the multimeter while it's set to the ammeter setting, which measures the current, between the trailer connector and the brake control.

Depending on the diameter of your trailer's brakes you should get the following readings:

Brake diameter 10-12″

• 2 brakes - 7.5-8.2 amps
• 4 Brakes - 15.0-16.3 amps
• 6 brakes - 22.6-24.5 amps

Brake diameter 7″

• 2 brakes - 6.3-6.8 amps
• 4 Brakes - 12.6-13.7 amps
• 6 brakes - 19.0-20.6 amps

If your trailer fails this test, you may need to check for corroded wires or loose connections. Be advised that if you don't know exactly what you're doing here you should take it to a professional as this can be highly dangerous work.

Furthermore, regular professional trailer inspections are required by law and a faulty trailer connection may signal that it's time your vehicle requires one.

Should I get a Proportional or Time Delay Electric Brake Controller?

Overall, a proportional brake controller is a more effective braking system as it directly replicates the brakes of your vehicle without the need for regular calibration depending on your tow load.

This means whether you slam on the brake pedal or apply gradual pressure, your tow vehicle's brakes will replicate the same gain, making driving a smoother process.

They are more expensive and require more involved installation but the quicker reaction times place less stress on your tow vehicle as well as are safer.

A time delay brake system needs to be calibrated on a load-by-load basis by the driver. They are a wiser choice for casual RV drivers as the installation is easier and they are cheaper across the board than proportional brake controllers.

That said, the time delay can cause more wear and tear on the brakes if you need to apply the brake pedal quickly.

The type of electric brake controller you need depends on several factors, such as how often you tow, the weight you're towing and your tow vehicle. In any case, both kinds will provide the necessary amount of control required for safe driving.

FAQs

How much does it cost to have a brake controller installed?

The cost of a trailer brake controller varies from between $60-$85 for a basic time-delay or proportional system respectively, with the price increasing up to between $240-$340 for a wireless or trailer-mounted system, both of which are proportional brake controllers.

If you decide to have your brake controller fitted professionally you can expect to pay between $225-$485 for parts and labor with an average cost of $300.

Do I need an electric brake controller if I purchase a tow package?

Yes, generally a tow package will only include a hitch platform, transmission and engine cooling, as well as a towing wiring harness and a sturdy frame to mount your hitch. The harness will allow you to connect a brake controller without having to splice it into your vehicle's wiring.

Enquire at your dealer, as some dealerships include onboard brake controllers in their tow packages.

How long do trailer brakes last?

On average brakes last between 6-24 months, this number depends on the weight of your load and the miles you clock up. It's wise to check the breaks every 6 months to ensure they're working optimally.

Final Thoughts

An electric brake controller is a necessary component if you're towing weight in excess of 751kg, providing safe and smooth transmission between your brake pedal and the brakes of your carriage.

Without one, you lack crucial control over the vehicle you're towing which is both dangerous and illegal.

Our step-by-step instructions make installation simple but if you're not familiar with your vehicle's electrics or would rather not run the risk of causing any unforeseen damage to your vehicle a professional can install them relatively cheap and quickly.

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