If your trailer’s brakes aren’t working, it can be a major safety hazard, especially at high speeds. A malfunctioning brake can cause the trailer to push the towing vehicle, risking a loss of control. Always check the brakes before towing any trailer, whether large or small.
In this post, we’ll explore the common causes of trailer brake failure and offer tips for diagnosing and fixing the problem.
Why Your Trailer Brakes Are Not Working – Causes
If your trailer brakes are not working, common causes could be rusty or loose electrical connections, worn brake pads, wiring problems, blown fuses, faulty brake controls, worn magnets, improper adjustments, or incorrect brake light signals.
Let’s take a closer look at the causes of trailer brakes not working, so you can identify the issue and take the necessary steps to fix it.
#1. Loose Electrical Connections
Most trailers have electric brakes. So if your trailer brakes are not working, the first thing you should do is check the electrical connections between the tow vehicle and the trailer and make sure that the electrical connections between the towing vehicle and the trailer are not loose.
Because loose or corroded connections can cause the trailer brakes to fail, also, make sure that your trailer is securely connected to the towing vehicle. Any trailer brake wiring system wears out after long periods of use, and if you are driving the trailer on rough roads, these connections may become loose due to the shaking.
#2. Blown Fuse
As you might know, the fuse box is installed to protect the electrical operation of the towing vehicle and the trailer and prevent any other short circuits. Where fuses related to the tow brake system and other functions are installed. But sometimes the fuse related to the electrical supply between the towing vehicle and the trailer blows and the trailer brakes may be unable to work.
Because a blown fuse causes no power supply. So when your trailer brakes are not working, don’t forget to check the trailer brake system fuses.
#3. Faulty Brake Controller
In many cases, a faulty brake controller can also cause trailer brakes not working. Because a faulty brake controller is unable to send electrical output signals to the trailer brake unit,
Many times, drivers forget to set the brake controller to the correct setting according to the trailer weight and braking requirements. Because the wrong setting of the brake controller can impair the functioning of the trailer brakes,.
#4. Worn Brake Pads
If the trailer brake pads are too worn, then this can also be a reason for the brakes not working. The worn brake pads do not apply pressure properly to the brake drum or rotor, so the brake pads lose friction or grip and the worn brake pads are unable to slow down or completely stop the rotating trailer wheel.
#5. Brake Fluid Problems
If your trailer has hydraulic brakes, check the brake fluid level in the master cylinder. Sometimes the brake master cylinder gets damaged or leaks, causing brake fluid to leak and the brake fluid level to drop.
So, when the brakes are applied, the hydraulic brake system does not generate the proper hydraulic pressure, causing the trailer brakes to not work. Also, leaking brake fluid in the hydraulic brake system can also cause this problem.
#6. Faulty or Worn Magnets
If you press the brake pedal on the towing vehicle and all electrical connections to the trailer’s brake system are properly connected, but if you still don’t see any response in the trailer brakes, the magnets in your trailer’s brake system are probably faulty.
This is because when an electrical signal is sent from the towing vehicle’s control unit to the trailer brake unit, the magnets in the trailer’s brake system are activated, which push the brake pads toward the drum, causing friction between the brake pads and the drum. But when the trailer brake system has faulty magnets, these can also cause the brakes to not work.
#7. Corroded Grounding Connection
Many a times, due to prolonged use, the trailer’s grounding connections get damaged due to water or weather effects. If your trailer’s grounding connection is faulty or damaged, your trailer’s brakes may also not work properly.
A poor grounding connection will not be able to properly transmit the electrical signal from the towing vehicle’s brake controller to the trailer’s brake system, which will prevent the trailer brake magnets from activating. Therefore, trailer brakes may also not work due to a poor grounding connection.
How To Check and Repair Trailer Brakes That Don’t Work?
To fix trailer brakes that are not working, you first need to identify the underlying problems and then take some possible steps to resolve them.
#1. Do A General Checkup
First, you should check that your trailer is securely attached to the tow vehicle. To check this, press the brake pedal on the towing vehicle before pulling the trailer and also try sliding the trailer back and forth.
#2. Inspect The Wiring & Connections
Your next step should be to check the wiring and fuses connecting the trailer brakes to the brake control. During the inspection, check that all connections are secure and free from corrosion.
Because a damaged connection or blown fuse can cause your trailer’s brake system to shut down. So if you find any damage in the wiring connections or fuses during the inspection, replace them with new ones.
#3. Check Brake Fluid Level
If your trailer has a hydraulic brake system, check the brake fluid level in the trailer’s master cylinder. Because low brake fluid levels impede the functioning of your trailer’s hydraulic brake system.
So if the brake fluid level is low, top it up. Also, if you notice any fluid leaks around the brake lines or brake components, get the leaks repaired properly.
#4. Check The Electric Brake Magnets
Keep in mind that most trailers use an electric brake system. In which the electronic signal magnet plays an important role. If your trailer also has electric brakes, check the brake magnet for any kind of malfunction or damage.
To test it, measure the resistance of the magnet using a multimeter. If its measurement shows a high reading, it indicates a bad brake magnet. If it does, replace the brake magnet with a new one.
#5. Check Brake Control Settings
Whenever you connect the trailer to the towing vehicle, adjust the setting on the tail brake control properly and make sure it is set correctly for your trailer’s braking system. Because incorrect settings of the brake controller can also interfere with the functioning of the trailer brakes.
#6. Test The Brake Signal
Check the brake signal with a circuit tester or multimeter to make sure that the brake signal is reaching the trailer brakes when the brake pedal is pressed.
If no signal is being received, there may be a problem with the brake switch or the wiring between the brake pedal and the trailer brakes. To fix this, replace the bad wiring or bad brake switch.
#7. Inspect Brake Components
If your trailer’s brakes still don’t work after doing all this, inspect the brake components themselves. Inspect for damaged brake shoes, springs, or other components in the trailer’s brake unit, and make sure the brakes are not excessively worn.
If you notice any damage to these components, replace the faulty component or make appropriate repairs.
Trailer Brakes Not Working But Lights Are Working
If your trailer brakes are not working but the tail lights are working, then it can also be due to the wrong settings of the brake controller. So firstly, you should check the brake controller settings. Then you have to check the brake wiring for any loose connections and also check the brake magnets for any worn or damaged ones.
If the problem still persists after all these checks, then check the ground connection on the trailer brakes. Because a poor ground connection to the trailer can impair the functionality of the brake system.
Also, check the brake fluid level. If the fluid level is low, then fill it up to the top. After doing all these checking procedures it will surely help you to solve this problem. However, it can be time-consuming and a matter of experience.
How to Test Trailer Brake Magnets with a Multimeter?
First you need to disconnect the power wiring from the brake magnets. Then, using a multimeter set to measure resistance, attach one probe to each terminal of the magnets. Properly functioning brake magnets should display a reading between 3 and 5 ohms when tested.
If the brake magnets’ resistance appears abnormal, this is a symptom of a short circuit or open circuit in the magneto. Additionally, inspect the brake magneto for other damage or wear.
Because this type of damage also affects its performance. So if the resistance reading appears abnormal during the multimeter test, replacing the brake magneto is a better option for safe and effective braking performance.
Why Are Electric Trailer Brakes Not Releasing?
If your trailer’s electric brakes are not opening, there are several possible causes that should be investigated and then worked to fix them.
- First, check the proper adjustment of your trailer’s brake control. If it is not properly adjusted, adjust it properly.
- Next, if you find any loose or corroded electrical connections, clean and tighten them and if the wires are damaged, replace them with new ones.
- Next, you should check the brake magnets. Use a multimeter to test its functioning. If the brake magnets fail the test, they replace the brake magnets with new ones.
- If your trailer’s brakes are still not opening, the problem may also be caused by a faulty brake controller, which will need to be replaced. Because a bad brake controller may be unable to send electric signals.
- You should pay attention to regular maintenance of your trailer’s brake system components. Because a lack of regular maintenance can also prevent the brakes from opening.
Frequently Asked Questions
Why are trailer brakes not engaging when I press the brake pedal?
Possible causes of this problem may include a faulty brake controller, disconnected wiring or faulty brake magnets. You should check these components to solve this problem. Repair or replace if necessary.
What to do if trailer brakes feel weak or sluggish?
Usually, weak or unresponsive trailer brakes are caused by low brake fluid, worn brake pads or air in the brake lines. To troubleshoot this you need to inspect the trailer brake fluid level and check the wear of the brake pads, and remove air from the brake lines if necessary.
Why do trailer brakes lock up excessively when braking?
If the brakes lock up when you apply the brakes on your trailer, the common causes are an out of adjustment brake controller, contaminated brake linings or faulty brake actuator. Therefore, attention should be paid to its regular maintenance for better trailer brake performance.
Banty Paul, owner and founder of Auto Repair Zone, brings over 14 years of hands-on experience in automotive repair and maintenance. This blog was created to share expert troubleshooting guides, repair tips, maintenance advice, and cost estimates for cars and semi-trucks.
