Trailer brakes are a critical safety feature, especially when towing heavy loads. If you’re hauling equipment, a car, or a camper, your trailer’s braking system needs to perform reliably. Trailer brake problems are often overlooked until you’re already on the road and something doesn’t feel right.
In this post, we’ll look at common trailer brake problems, how to diagnose them, and what you can do to repair or prevent them.
Troubleshooting Frequent Trailer Brake Problems
1. Brakes Not Engaging
If your trailer brakes aren’t engaging at all, it could be due to a failed brake controller, a blown fuse, or a broken connection somewhere in the wiring. Begin by checking for power at the trailer plug using a multimeter or test light. If power is reaching the trailer but not the brakes, inspect the wiring along the frame and at each brake assembly. Also, make sure the controller in your tow vehicle is properly powered and sending a signal.
2. Brakes Lock Up or Drag
When trailer brakes lock up or feel like they’re dragging, it often points to the gain setting on the brake controller being too high or inconsistent grounding. You may also have brake magnets that are sticking or malfunctioning. Try reducing the gain, then clean and tighten all ground connections. If the issue persists, test the magnets and wiring for internal faults or excessive wear.
3. Brakes Feel Too Soft or Too Strong
Soft brakes may indicate worn pads or an underpowered signal from the controller, while brakes that feel too aggressive could mean the gain is set too high. Recalibrating your brake controller is a good first step. Most modern controllers allow for quick adjustments while driving, so you can find the right balance between braking power and smooth stopping.
4. Brake Fade on Long Descents
If your brakes start strong but lose power during long or steep downhill stretches, they may be overheating. This is called brake fade, and it’s often caused by worn components, misadjusted brakes, or poor braking habits. Try downshifting to use engine braking on descents and inspect your brake shoes or pads for excessive wear or glazing.
5. Inconsistent or Jerky Braking
Jerky or inconsistent braking is usually tied to wiring issues, loose connections, or a faulty controller. These problems can cause the brakes to engage unevenly or sporadically. Go over all connectors, grounds, and harnesses to make sure everything is secure and corrosion-free. If everything looks good and the problem continues, the controller itself may need replacement.
How to Diagnose Trailer Brake Problems
A thorough diagnosis is key to identifying and resolving trailer brake problems. Here’s a more detailed step-by-step approach:
1. Visual Inspection
Begin with a complete visual check of the trailer’s brake system. Look at the brake assemblies, wiring harnesses, connectors, and mounting hardware. You’re looking for signs of corrosion, frayed or pinched wires, worn brake pads, loose bolts, or damage to the drum or rotor surfaces. Pay special attention to areas where the wiring runs along the frame, as these spots are especially prone to wear and exposure.
2. Test the Brake Controller
Inside the tow vehicle, ensure the brake controller is functioning properly. It should power on, respond to input (such as pressing the brake pedal or using the manual override), and display voltage output. Use a voltmeter or built-in diagnostics (if available) to verify that the controller is sending appropriate voltage to the trailer. If the controller appears dead or unresponsive, check the fuse and wiring leading to the unit.
3. Use a Multimeter
A multimeter is one of the most effective tools for diagnosing electrical brake systems. Test the output at the tow vehicle’s 7-way connector while activating the brakes. Then move down the wiring path to the trailer’s connector and finally to each brake assembly. If power is lost along the way, you’ve identified the general location of the problem, typically a broken wire, corroded terminal, or bad ground connection.
4. Inspect Hubs & Drums
For electric brake systems, remove the hub/drum assembly and inspect the internal components. Check the condition of the brake shoes, magnets, return springs, and wiring. If the magnets are worn unevenly or have grooves, they may not make full contact, reducing braking power. Use an ohmmeter to test magnet resistance according to the manufacturer’s specs.
5. Check Fluid & Actuator (for Surge Brakes)
For hydraulic surge brakes, inspect the master cylinder for proper fluid level and look for leaks along the brake lines. Check that the actuator compresses and releases smoothly when force is applied and removed. Any sticking, sponginess, or leaks in the system will reduce braking effectiveness and should be addressed immediately.
By following these steps, you can isolate the most common trailer brake problems and make more accurate, efficient repairs.
Why Trailer Brakes Fail
Like any mechanical system, trailer brakes are subject to wear, environmental damage, and neglect. Here are some of the most common reasons they stop working or perform poorly:
Corrosion and Moisture
Corrosion and moisture can seize moving parts or damage electrical connections. Brake components are often exposed to the elements, including rain, snow, and road salt. Over time, these conditions can cause rust to develop on metal parts and connectors. Water intrusion into electrical systems can short out wires or cause terminals to oxidize, resulting in poor performance or complete failure.
Worn-Out Brake Pads or Shoes
Brake pads or shoes wear down over time, reducing braking power. As these friction materials wear thinner, they become less effective at slowing the trailer. This can lead to increased stopping distances and overheating, which may cause warping of the brake drum or rotor. Regular inspection and replacement are essential to maintain proper braking performance.
Brake Controller Malfunctions
Brake controllers can malfunction or fall out of calibration. These devices regulate how much braking force is sent to the trailer based on your vehicle’s braking input. A controller that isn’t properly set may apply too much or too little braking, or none at all. Faulty wiring, software glitches, or internal component wear can all affect performance, making troubleshooting essential.
Wiring Issues
Wiring issues, especially on electric brake systems, can interrupt signals from the tow vehicle. The wiring harness connecting the tow vehicle to the trailer can become damaged from road debris, vibration, or poor routing. Frayed wires, loose connections, or corrosion can cause intermittent signal loss, weak braking force, or total failure. Trailer wiring should be protected and inspected regularly.
Surge Brake Failures
Surge brake systems may suffer from fluid leaks or sticking actuators. These systems rely on hydraulic pressure created when the trailer compresses against the tow vehicle. If the master cylinder or brake lines leak fluid, pressure is lost and the brakes won’t engage properly. Additionally, actuators can stick due to corrosion or internal damage, causing the brakes to stay applied or not engage at all.
Lack of Maintenance
Infrequent maintenance can cause small problems to grow unnoticed. Trailers are often used seasonally or intermittently, which can lead owners to skip regular inspections. Brake components can wear, seize, or corrode between uses. Without routine cleaning, lubrication, and adjustment, even minor issues can escalate into unsafe conditions on the road.
Types of Trailer Brake Systems
Understanding what kind of braking system your trailer uses helps narrow down the source of the problem:
- Electric Brakes: These use magnets to activate brake shoes when signaled by the tow vehicle’s brake controller.
- Surge Brakes (Hydraulic): These activate when the trailer pushes forward against the hitch during deceleration, compressing a hydraulic actuator.
- Electric-Over-Hydraulic (EOH): A combination system that uses electric signals to control a hydraulic pump.
Each type has its own common issues. Electric brakes often suffer from wiring problems or weak magnets, while surge systems are prone to fluid leaks or sticking components.
At Four Winds Trailers, we carry a wide selection of trailers equipped with various braking systems and axle configurations designed to handle heavier loads and reduce wear. Choosing the right setup from the start can help minimize many of the trailer brake problems discussed in this guide. For example, our car hauler trailers come standard with brakes on both axles, giving you extra stopping power and added protection when hauling heavier loads. This extra braking capacity provides greater control and safety while transporting vehicles or other heavy cargo.
Signs of Trailer Brake Problems
You don’t always need to see a warning light to know there’s an issue. Watch for these signs:
- Brakes feel weak or don’t seem to engage. This could be due to worn brake pads, a malfunctioning controller, or a failure in the brake activation system. If the trailer doesn’t seem to slow down when braking, it’s a clear warning sign.
- The trailer pushes against the tow vehicle when braking. If it feels like the trailer is “shoving” your vehicle forward during stops, it may mean the trailer brakes aren’t activating at all or are severely underperforming.
- Squealing, grinding, or scraping noises. These sounds can indicate worn-out pads or shoes, debris in the drum, or metal-on-metal contact, all of which need immediate attention.
- Your trailer pulls to one side when braking. Uneven braking is often caused by one brake assembly working harder than the other, due to mechanical issues, uneven wear, or electrical imbalances.
- Brake controller displays error messages or behaves inconsistently. Error codes, blinking lights, or fluctuations in brake intensity can all point to underlying wiring or calibration problems in the braking system.
Preventive Maintenance Tips
- Inspect brake components regularly for wear or damage.
- Keep electrical connections clean and protected from moisture.
- Grease wheel bearings and hubs as recommended.
- Check and adjust brake settings before every trip.
- Use dielectric grease on all wiring connections to prevent corrosion.
When to Seek Professional Help
Some brake issues are too serious or complex to fix in the driveway. If your trailer brakes still aren’t functioning properly after basic troubleshooting, it might be time to call in a professional. If you’re in the Bowling Green, Kentucky area, Four Winds Trailers offers expert trailer service and repair to get you safely back on the road.
Avoiding Trouble Before It Starts
Trailer brake problems can range from minor annoyances to serious safety hazards. Knowing the signs and taking the time to inspect and maintain your braking system can prevent breakdowns and accidents.
Need help with more than just brakes? Take a look at our complete guide to common trailer problems, where we cover everything from electrical issues to tires, lights, and more, all aimed at keeping your trailer safe and road-ready.