1. Air Supply:
* Low air pressure: This is the most common cause. Check the air pressure gauge on your tow vehicle. If it's low, you need to address that issue first – low pressure won't allow the trailer brakes to function properly. Look for leaks in the air lines, or a problem with your compressor.
* Air leaks: Check all air lines from the tow vehicle to the trailer for leaks. Use soapy water to help locate leaks; bubbles will form where air is escaping. Leaks can be in the lines themselves, at connections, or even in the brake chamber itself.
* Air line disconnected: Ensure the air line is securely connected at both the tow vehicle and the trailer.
2. Brake Chamber Issues:
* Diaphragm rupture: The diaphragm inside the brake chamber might be torn or damaged, preventing it from building pressure. This requires replacing the brake chamber.
* Stuck pushrod: The pushrod connecting the brake chamber to the brakes might be seized or stuck, preventing movement. Try manually operating the pushrod (carefully!) to see if it's free.
* Brake chamber malfunction: The brake chamber itself could be faulty. This is less common but possible, requiring replacement.
* Low voltage issue (if electric over-pneumatic): Some trailer brake systems use electric actuators to control pneumatic brakes. If your system is this type, there could be a low voltage problem preventing the electric actuator from functioning.
3. Electrical Issues (if electric brakes):
* Wiring problems: Check all wiring connections between the tow vehicle and trailer. Look for loose, broken, or corroded wires.
* Brake controller malfunction: If you have a brake controller in your tow vehicle, it might be malfunctioning. This needs to be checked and possibly replaced.
* Fuse blown: Check the relevant fuses in both your tow vehicle and trailer.
4. Safety and Parking Brakes:
* Parking brake engaged: Ensure the trailer's parking brake is disengaged.
* Tow vehicle brakes: If your tow vehicle brakes are significantly weaker than usual, it can impact trailer brake function in some systems.
Troubleshooting Steps:
1. Check air pressure: This is the FIRST step.
2. Inspect air lines: Look for leaks and disconnections.
3. Manually check pushrod: (if safe and accessible) see if it's free-moving.
4. Check electrical connections (if applicable): Ensure all wiring is secure.
5. Check fuses: In both the tow vehicle and trailer.
Safety Warning: If you are unsure about any of these steps, do *not* attempt repairs yourself. Improperly functioning brakes are extremely dangerous. Take your trailer to a qualified mechanic for diagnosis and repair.
