Troubleshooting Passenger Side Trailer Brakes Not Activating Correctly
Question:
I recently noticed that none of my trailer brakes were functioning. After a quick inspection I came across a few broken connections on the driver side brake connections. I replaced the connections and the brakes were functioning again. While doing a slow road test it became clear the passenger side brakes were still not functioning. During the first inspection I found no broken connections on that side. I decided to replace the connections where the ground and power wires exit the axle and connect to the wire feeding the brakes. With the trailer jacked up I had my wife apply the brakes in the truck. While she was doing this I could clearly hear power going to both passenger side brakes but I was able to spin the brakes while she was applying pressure. I then had her just apply pressure and after about 6-8 seconds of a light buzzing sound I could hear the brakes engage. I have not been able to locate a spot where the ground could be disturbed between the driver side and passenger side of the trailer. What do you think could be causing this and how much do you think a repair would be? Thank you,
asked by: Matt H
Expert Reply:
The brake magnets themselves could be bad in your passenger side brake assemblies. Take off your hubs and inspect them to see what their condition is and replace if necessary. If they look they are worn to the point that copper wire is showing they need to be replaced.
Or if you do not want to remove the hub you can, with the tow vehicle connected to the trailer, connect a multimeter inline with the brake wire somewhere between the trailer connector and the trailer brakes. If your trailer only has 2 brakes, then the amps should read 7.5 to 8.2 at 12 volts. For 4 brakes, 15 to 16.3 amps and for 6 brakes, 22.6 to 24.5 amps. If your amperage reading is greater or less than the specified range for your brakes, then the magnets may need to be replaced.
The next test is to test the brake magnet individually. Testing individual brake magnets for proper function can be accomplished by severing the magnet wires and connecting the ammeter between the positive terminal of a 12 volt battery and one of the magnet wires, it does not matter which one, then connect the other magnet wire to the negative battery terminal. Each brake magnet should read 3.2 to 4.0 amps at 12 volts.
To test the magnet for a short, touch the base of the brake magnet to the negative post of a 12 volt battery. Then, connect one of the brake magnet wires to the negative lead of a multimeter, and the positive lead of the multimeter to the positive post of the battery. If any amperage is detected the magnet is shorted and will need to be replaced.
I have attached an article on testing brake magnets for you to check out.
