How to Test Individual Trailer Brake Magnets with Battery and Circuit Tester

Published 08/07/2018

Question:

what is the current through one brake magnet? I work part time at a camper sales lot and do repairs on brakes and other items and would like to build a tester to to check the brakes circuit before delivery to the customer.

asked by: Vernon C

Helpful Expert Reply:

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. Check the amperage. If the amperage is greater than the specified amount (see specifications below), replace the magnet. If the reading is less than the specified amount, the leads are bad and the magnet should be replaced.

10 and 12 Inch Brake Magnets
3.2-4.0 Max amps at 12-13 volts

7 Inch Brake Magnets
3.0-3.2 Max amps at 12-13 volts

expert reply by: Jameson C