Electric Brake Magnet Troubleshooting and Testing

Updated 06/07/2018 | Published 06/06/2018

Question:

Looking at the specs for various brake size magnets, you give the spec as Max amps 11-13 volts. What exactly does that mean, is there a max amp that is not stated for a voltage of 11-13, or do you actually mean that the amperage should be 11-13 max. I realize the general public does not know the difference, but to someone who understands electricity a little and that voltage and amps are not the same, your spec is confusing.

asked by: Jeff

Expert Reply:

You are correct that the amps and voltage are not the same. If you put your multi-meter like # PT89ZR between a spliced brake output wire on your vehicle between the brake controller and the trailer connector socket with your trailer connected to your vehicle, you should get an amperage reading of 7.5 to 8.2 amps for a single axle trailer, 15.0 to 16.3 amps for a tandem axle trailer, or 22.6 to 24.5 amps on a triple axle trailer. If the amperage reading is less then the specified amounts listed, then the leads are bad and the magnets should be replaced.

I've also attached an article to further explain this and assist with testing the individual magnets resistance using an ohmmeter function on the multi-meter.

expert reply by: Jason S