Electric Brakes In Camper Trailers: How Do They Work?

Electric trailer brakes are a type of braking system that uses electricity to slow down or stop a vehicle. They are commonly found on camper trailers or boat trailers and are known for their ease of installation and maintenance. When the brake pedal is pressed, a brake controller transmits electric power through the trailer plug to the brake system, with each brake on the axles having a separate wire. This results in the generation of power that forces the wheels to stop rotating. Electric trailer brakes offer several advantages over traditional hydraulic brakes, including increased efficiency, suitability for all weather conditions, and lower repair and upkeep expenses.

Electric brakes vs hydraulic brakes

Electric brakes and hydraulic brakes are two different types of braking systems used in trailers. Electric brakes use electromagnets to actuate the drum brakes, while hydraulic brakes use the trailer's natural momentum to activate the braking system.

Electric Brakes:

Electric brakes provide additional ease of use and more braking control compared to hydraulic brakes. They are more simple and require a brake controller in the cabin of the tow vehicle. Electric brakes use electromagnets to activate the drum brakes, and the driver can control the electricity to the brakes using the brake controller and the brake light circuit. When electricity is turned on, it magnetizes the brake magnet, which is attracted to the drum face. This friction causes the drum to rotate, pushing the shoes out against the drum and creating the braking force.

Hydraulic Brakes:

Hydraulic brakes, also known as surge brakes, use the trailer's natural momentum to activate the braking system. When the driver steps on the brake in the tow vehicle and slows down, the trailer pushes against the hitch, pressing a hydraulic cylinder. The more the vehicle slows down, the more pressure is applied to the trailer brakes. Hydraulic brakes are often found on camper or boat trailers.

Comparison:

One of the main advantages of electric brakes is their ease of installation. Most trucks, vans, SUVs, and RVs made since the mid-1990s are set up to use an electronic trailer brake controller, with a factory-installed "quick plug" under the dash. Electric brakes also have lower parts costs and require less maintenance than hydraulic brakes. Hydraulic brake owners must maintain brake lines from corrosion and maintain the hydraulic actuator and brake assemblies.

However, one disadvantage of electric brakes is the potential for wires to corrode, especially when submerged in water, making them less suitable for boat trailers. In contrast, hydraulic brakes are more common on boat trailers due to their ability to withstand submersion. Additionally, electric brakes require a brake controller, while hydraulic brakes operate independently.

How to install electric trailer brakes

Installing electric trailer brakes is a complex process that requires careful attention to detail. Here is a step-by-step guide on how to install electric trailer brakes:

Firstly, ensure you have the correct tools and a suitable workspace. You will need items such as a drill, screws, and wire connectors, as well as a safe, open area to work in.

Next, disconnect the negative cable from your vehicle's battery to prevent any injury or damage to the electronics during the installation process.

Now, you need to determine the best location for the brake controller on your dashboard. It should be easily visible but not obstruct your view of the road. Avoid installing it close to sensitive electronics like a CB radio. Once you've found the right spot, use the mounting bracket as a template to mark the drilling points.

Drill holes for the mounting bracket, being mindful not to damage any electronics behind the dashboard. Remove the dashboard panel if possible to avoid unnecessary risks.

Fasten the brake controller into place using the provided screws. Be careful not to overtighten or strip the holes. Attach the brake controller to the bracket securely.

The next step is to plug in the brake controller. Use a vehicle-specific wiring harness to connect the brake controller to your vehicle. One end plugs into the vehicle's factory harness under the dashboard, and the other end plugs into the brake controller. Refer to your vehicle's diagram to locate the factory wiring harness.

Now, you need to connect the brake controller wiring. Strip and separate the wires as needed. Match the wires by colour: blue to blue, red to black, white to white, and white with a blue stripe to red. Use wire connectors like butt connectors or quick splice connectors to join the wires securely.

Finally, attach the power wire from the brake controller to the vehicle's battery. Locate the power feed wire near the fuse box and attach it to the auxiliary power terminal. Reconnect the negative battery cable, and your installation is complete.

You may also need to calibrate and adjust the settings of the brake controller, following the manufacturer's instructions. Test the trailer brakes to ensure they are functioning correctly and make any necessary adjustments to the output and sensitivity.

How to calibrate electric trailer brakes

Electric trailer brakes work by activating electromagnetic brake drums to create attrition and slow the trailer down. While some trailer brakes work independently, electric trailer brakes require a connection to the tow vehicle's power and a brake control unit or electric brake controller.

To calibrate a trailer brake controller, follow these steps:

• Park your vehicle on a level surface.
• Plug your trailer into your tow vehicle.
• Allow the brake controller to calibrate. Most brake controllers are self-calibrating and will flash a light or signal to indicate when the unit is calibrating and when calibration is complete.
• Adjust the brake controller to fit the vehicle, trailer, and load size.
• Set the brake controller to the gain level and sensitivity recommended by the manufacturer.
• Test the brake controller and brakes at 25 mph. If the vehicle stops slowly, increase the trailer brake gain. If the brakes lock up, decrease the gain.

How to test if electric trailer brakes are working

Electric trailer brakes are an essential safety feature, so it's important to ensure they are working correctly. Here is a step-by-step guide on how to test if your electric trailer brakes are functioning properly:

Step 1: Check the Trailer Wiring Harness

First, ensure that your trailer is securely coupled to your vehicle. Check that the trailer wiring harness is plugged into your vehicle. The brake controller requires a power source from the vehicle and a connection to the trailer brakes to function correctly. It is also important to park your vehicle and trailer on a level surface in a safe, open area with plenty of stopping distance and no traffic around.

Step 2: Allow the Brake Controller to Calibrate

After connecting the trailer, the brake controller may need to calibrate. Most brake controllers are self-calibrating and will indicate this process with a flashing light or signal. If your brake controller does not require calibration, proceed to the next step.

Step 3: Adjust Personal Settings

Some brake controllers offer personal settings that can be customised to your preference, such as the angle of the interface, the brightness of the screen, and the location of the brake controller itself. Adjust these settings before moving on.

Step 4: Set the Maximum Output

Set the maximum output, which is the highest amount of power the brake controller will apply to the trailer brakes. This setting will depend on the load size. Press and hold the vehicle brake pedal, and set the output to the starting value specified in the instructions.

Step 5: Test the Trailer Brakes

Now, test the trailer brakes by driving forward at a moderate speed (around 25 mph) and applying the brakes. If the vehicle stops too slowly, increase the maximum output. If it stops too abruptly or locks up, reduce the output. This test will help you adjust the brake controller to ensure optimal braking performance.

Step 6: Adjust the Sensitivity Level

The sensitivity setting determines how aggressively the brake controller will apply the brakes. Test the trailer brakes again by driving at 25 mph and pressing the brake pedal. If the vehicle stops too slowly, increase the sensitivity. If it stops too abruptly, lower the sensitivity. By fine-tuning these settings, you can ensure that your trailer brakes activate smoothly and efficiently.

Step 7: Manually Activate the Trailer Brakes

Most trailer brake controllers have a manual activation button that allows you to activate the trailer brakes without applying the vehicle brakes. This feature can be useful for minor corrections, such as reducing trailer sway or slowing down gradually on a hill.

Additional Testing Methods

While the steps above cover the basic procedure for testing your electric trailer brakes, there are also more advanced testing methods you can employ if you suspect a malfunction or want a more comprehensive diagnosis. These methods may require specialised tools like voltmeters, ammeters, or multimeters, and it is recommended to consult a qualified automotive electrician for assistance. Here are some additional testing procedures:

Testing with a Multimeter

You can use a multimeter to test the trailer brake magnets and check the amperage of your trailer braking system. Connect the multimeter inline with the blue wire exiting the back of the brake controller. Check the amperage, and compare it to the specified amount in the manufacturer's instructions. If the amperage is higher than specified, replace the magnet(s). If it is lower, the leads may be faulty and need replacement.

Testing Individual Brake Magnets

You can also test each brake magnet individually for proper amperage. To do this, sever the magnet wires and connect the ammeter between the positive terminal of a 12-volt battery and one of the magnet wires. Then, connect the other magnet wire to the negative battery terminal. Check the amperage, and replace the magnet(s) or leads as needed, based on the specified amounts.

Testing for a Short

To check for an internal short in a brake magnet, touch the base of the magnet to the negative post of a 12-volt battery. Then, connect one of the magnet wires to the negative lead of a multimeter and the positive lead to the positive post of the battery. If any amperage is detected, the magnet has an internal short and needs replacement.

Testing Brake Magnet Resistance

You can use an ohmmeter (a function on your multimeter) to check the resistance between the brake magnet wires. Compare the resistance reading to the specified range for your brake magnet size. If the resistance is outside the specified range, the magnet will need to be replaced.

Testing Voltage and Amperage

You can use a voltmeter and an ammeter to measure the voltage and amperage in the system, respectively. Connect the voltmeter to the magnet lead wires to measure the voltage. With the engine running, the voltage should gradually increase to about 12 volts as you slowly actuate the controller bar. For amperage measurement, disconnect the blue wire of the controller and put the ammeter in series into the line. Compare the amperage reading to the specified values for your system.

How to fix electric trailer brakes

Electric trailer brakes work by using a magnet to spread the brake shoes against the brake drum, creating friction and slowing the trailer down. When electricity is applied, it magnetises the brake magnet, which is attracted to the drum face. As the magnet contacts this area, the friction causes it to rotate, which moves the actuating arm and pushes the shoes out against the drum. These shoes have a special brake pad material on them that resists the heat caused by the friction.

Now, if you're experiencing issues with your electric trailer brakes, there are a few things you can check and some troubleshooting steps you can take to try and fix the problem.

Troubleshooting and Fixing Electric Trailer Brakes:

Check the Trailer Connector:

• Open the trailer connector by removing any screws and sliding the cover back.
• Locate the wire that controls the electric brakes (usually the blue wire).
• Plug the trailer connector into the tow vehicle connector and ask an assistant to press the brake pedal.
• Attach a 12-volt test light's ground clip to a bare metal portion of the trailer's frame.
• Touch the probe on the test light to the screw where the blue wire connects to the trailer connector.
• If the test light does not light up, the connector is faulty and should be replaced.

Test the Electric Brake Wiring:

• Reassemble and reconnect the trailer connector to the tow vehicle.
• Have an assistant press the brake pedal.
• Locate the wire controlling the electric brake at each wheel, where it enters the drum backing plate.
• Connect the ground clip on the test light to the trailer's frame.
• Use the probe to pierce the insulation on the wire at each wheel.
• If the test light does not light up, there is likely a break or fault in the wiring between the connector and the wheel.
• Examine the wiring and repair or replace any damaged wires.
• If the test light illuminates but the trailer brakes still don't engage, the magnet inside the brake drum may be defective and need replacing.

Replace the Brake Drum Magnet:

• Lower the front of the trailer and place jack stands underneath the frame to support it.
• Raise the front of the trailer so the wheels are off the ground, then remove the wheel and tire.
• Remove the grease cap, cotter pin, and castle nut from the center of the hub.
• Remove the brake drum (the outer wheel bearing will come off with it, so be careful).
• Examine the brake shoes and locate the magnet, which is usually attached to one of the shoes.
• Remove this shoe to disconnect the magnet, taking care to note how it is assembled for easier reassembly.
• Remove the springs, self-adjuster, and pins that attach the brake shoe to the backing plate.
• Cut the wires connected to the magnet and remove it.
• To install the new magnet, connect the wires to the old wire ends using barrel crimp connectors, then reinstall the brake drum components in the reverse order of removal.

By following these steps, you can identify and address common issues with electric trailer brakes, ensuring they are in proper working condition for safe towing.

Frequently asked questions