Testing the Amperage Draw of Trailer Brake Magnets

Question

Question:

I have all my brakes removed from my 5th wheel trailer and am ready to install all new brake assemblys. All I have at each axle is the wiring for the new magnets to be installed to, can I check for any amp at these wires before I hook up the magnets.

asked by: Garry

0

Expert Reply:

You can check for amperage but depending on the size of the magnets they will draw a certain amount no matter what the amperage is on the wire. I have included a link to an FAQ article that should help you. You will want to look at the section titled Testing Individual Brake Magnets.

10 and 12 inch brake assembly magnets should show 3.2 to 4.0 amps max at 12 to 13 volts per magnet. 7 inch brake assembly magnets should show 3.0 to 3.2 max amps at 12 to 13 volts per magnet. You can use a multimeter like # PT89ZR if needed.

expert reply by: Michael H

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Answer 1

Electric brakes have 2 wires located at the back. One is for power and the other is for ground (it doesn't matter which is used for which function). The ground wires should be connected to the trailer frame. The only other place that would carry…

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Answer 2

If the brake magnet is worn to the point that the windings are visible then you know it's time to replace the magnet. However, magnets can also fail without the visible signs of wear. Check out the FAQ article I attached on testing brake magnets…

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Answer 3

I think you are going in the right direction. I would definitely replace the 14 gauge wire going to the trailer brake magnets with 10 gauge wire or larger. Usually larger than 10 gauge is hard to get into the trailer connector though. I would also…

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Answer 4

Self-adjusting brakes like the etrailer.com Electric Brake Kit #AKEBRK-35-SA that you recently installed do require an initial calibration, which it sounds like you have already done. From there the brakes will continue to set themselves to the…

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Answer 5

You said you checked the brake magnets. When inspecting them did you notice if the windings inside the magnets are showing? If so this is most likely the reason that the short is showing up on the controller when the vehicle is moving. This would…

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Answer 6

On this page (typically below the product links) there is a helpful link section that will have the install instructions fo the Hopkins Breakaway kit part #20400 that you referenced. I also attached an install video that shows the kit installed as…

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Answer 7

You likely can use any replacement switch since all they do is complete a circuit when the pin is pulled out. One wire on the switch should be connected to the positive battery terminal on the trailer. The other will tee into the wiring leading from…

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Answer 8

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 9

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 10

Hey Richard, thanks for reaching out! The Dexter DX7.5 Drop-N-Go Brake Actuator #099-175-00 is a great option for a replacement actuator because it's a direct replacement for the common Model 60 actuators that were popular in the '90s.…

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Answer 11

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose #8-258-5UC1. If the inner bearings are marked…

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Answer 12

Traditionally, trailer manufacturers did not use electric brakes on boat trailers because the brake magnet wiring and trailer wiring did not always have the best insulation or water protection. These days, more and more manufacturers are using…

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Testing the Amperage Draw of Trailer Brake Magnets

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