Trailer Brakes are Weak on a New Camper Trailer

Question:

I purchased a new camper three years ago. from day one I have had brake problems. The brakes did not all come on together. One brake out of the four would come on harder than the other three. Sometimes they all seem to come on very little. So far I have had three axles replaced, no difference. With my dealers help the Manu. Took the camper back and re-worked it. New larger axle assembly, brakes-axles- tires. They tested and said it was perfect. We came camping this weekend and coming down a small hill the one brake locked up. When they tested the brakes it was in Indiana, no hills that I am aware of. I live in central pa lots of hills. Do you think that the brake controller would be at fault. I have no problem buying a new one if I knew for sure. I am an electrical-Electronics technician- I tested controller without and with brakes hooked up. Power was always the same at each wheel. The wiring on the trailer is 14 awg,to small?

asked by: Rob K

Helpful Expert Reply:

The 14 gauge wire is too small. As an electrician you are aware that small gauge wire can choke out the amperage needed to run some electrical devices. Trailer brake magnets wiring should be using 10-gauge wire. We sell 10-gauge wire by the foot, # 10-1-1.

If all the wiring is intact with no pinched or frayed wires, then make sure the magnet grounds are attached to clean and corrosion free bare metal surfaces. I am also wondering if while testing the brakes if they also adjusted them out properly. The brakes need to be adjusted out to the point where you can hear a slight but constant drag of the pads on the drum when the wheel is turned.

To test the brake controller, in the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2992 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override. If it shows power at idle, then there is something wrong with the controller and it will need to be replaced.

If it tests fine, then reconnect the blue wire. Then move on to the truck side trailer connector. Many times, dirt or corrosion can cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out.

You can test the brake output pin and it should only show power with the manual override. If it shows power any other time, then there is a short somewhere between the connector and the brake controller you will need to track down.

If the truck side checks out fine, then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.

You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets, you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.