Which Wire on a Trailer Brake Magnet is the Power and Which is Ground

Updated 07/16/2015 | Published 07/15/2015

Products Featured in This Question

Hopkins 7-Way Molded Trailer Wire Connector - 11' Long

(187)

$57.92

10 Gauge Wire - Blue Primary - Per Foot

(104)

$1.77

Replacement Breakaway Switch for Bright Way Trailer Breakaway Kits

(160)

$24.03

Question:

The brake magnet has 2 wires is 1 a neg. Ground and the other pos. 12 volts. I have a 18 foot utility flat bed tongue hitch with 2 3500 axles. Looks like brakes werent hooked up. Case for 12v battery is there, the pull switch needs to be replaced. 2 blue wires from passenger drum goes thru axle but not hooked up to other drum. Needs 2 wires to go to front. Not sure if magnets work. Can I put 12v to mag. To see if wheel stops turning. 12v to 1 wire and ground to other. I have a ford 3500 a 7 pin female at back. The trailer has 4 pin, need to change that to pin. Does all of this sound right correct whats wrong. Thank you.

asked by: Nick G

Expert Reply:

Trailer brake magnets have two wires ran to them. Either can be used as the positive side as long as the other is grounded. To test your magnets, you would want to apply 12 volts to one of the wires and ground the other wire. You should hear them grab the drum and start humming.

For a replacement breakaway switch, you could use the # 3802348.

For an 11 foot 7-way that you could wire your trailer to you would want the part # HM20048. You will need to attach the current wires of your trailer to this connector and then run the brake output circuit to the brake assemblies. You would want to use 10-gauge wire like # 10-1-1 for that.

I attached a couple help articles for you to check out as well.

expert reply by: Jameson C