Trailer Brakes are Weak and Will Not Lock Up on Horse Trailer

Question:

We have had all components changed in our brakes and even add another break axel to our tandom horse trailer. The issue we are haveing is that the new beaks will not lock up with the break box depressed nor will it hold the truck on a slight hill. Had read a formum that new breaks need to be warn in is that true. Have new grounds for breaks. They are working but the resistance is not enough to lock them on pavement nor hold our truck on a hill.

asked by: Mike C

Expert Reply:

Your trailer brakes probably have to be adjusted. New brakes will not be adjusted out far enough and old brakes if not regularly adjusted will eventually start to make less and less contact with the inside of the drum. You want to adjust the brakes so that you hear a slight but constant drag of the pads on the drum. To see how to manually adjust trailer brake assemblies check out the video I attached, fast-forward to the 4:35 mark of the video.

If the brakes are adjusted properly then they may not be getting the voltage needed or the wire gauge may be too small, especially when adding additional brakes. You might want to go to 10 gauge wire such as # 10-1-1 if not using it already.

To see how much output the brake controller is putting out you can use a multimeter such as # PT89ZR. Check the brake output pin on the vehicle side connector. Have someone set the power output on the brake controller to the highest setting and then apply the manual override lever. You should be seeing around 12 volts at the trailer connector.

If you are seeing less than 12 volts then there is an issue somewhere between the trailer connector and the brake controller. You can make sure the vehicle and trailer side connectors are clean and free of corrosion inside where the wires attach and outside on the pins. Also inspect the wiring from the back to the front as much as possible and fix any damaged wires. To test the brake controller you can follow the help articles I have linked.

Also make sure that the brake controller is mounted according to the specifications in the instructions if it is a proportional brake controller.

If you are getting 12 volts at the trailer connector then you can plug the trailer in and keep testing for voltage on the brake circuit wire. Check for any breaks or pinched wires and repair as needed.