Testing Trailer Brake Magnets When Brakes Are Not Working

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Question:

1982 Chevy K10 Blaze, I have power from brake at seven way to trailer, want test magnets and wiring to each of four brakes in my trailer.

asked by: William H

0

Expert Reply:

The first test you will want to do is to test the amperage of the trailer braking system with a multimeter, like # PT89ZR. First, you will connect the ammeter inline with the blue wire exiting the back of the brake controller. Check the amperage. If the amperage is greater than the maximum amount listed in the attached chart, you will want to replace the magnets. For a trailer with 4 brakes and 10 or 12 inch drums, the maximum amperage at 12-13 Volts should be between 15.0-16.3 amps. For 4 brakes with 7 inch drums, the maximum amperage should fall between 12.6-13.7 amps.

If this test shows the amperage at a normal measurement, you can begin testing the individual brake magnets for proper amperage. You will also want to test the magnets for a short and for resistance. I have attached a help article on testing trailer brake magnets for you.

expert reply by: Victoria B

0

Answer 1

It depends on what the brake controller output is set to. If you have the brake controller set to the maximum then there should be about 12 volts at the brake magnets. To see if the brake magnets are drawing the correct power set the brake controller…

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Answer 2

Its not uncommon for there to be slight voltage drop off over a certain distance but with the brake controller set to the maximum you should still be getting 12 volts at the brake magnets. We need to determine if the low voltage is coming from the…

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Answer 3

Testing your trailer brakes for proper function on the test bench will require a multimeter that can display readings for both amps and ohms, such as part # PT89ZR. (Some brake controllers, such as the Tekonsha P3, have built-in test functions.) You…

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Answer 4

If you are only getting 1.5 volts at your brakes then there is an issue, but there is not a fuse that controls the brakes. There are a number of possible issues so you will need to find out if the issue is on the brake controller, truck, or trailer.…

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Answer 5

I do not recommend that you bypass the break away system because in many states it is a requirement to have a working break away system. Trailer brake magnets will have one power wire and one ground. The power output from a break away system will go…

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Answer 6

Yes. There should always be a very light power on your brake controller wire. However, it should be extremely minimal. As you increase in power using the manual override, you should see an incandescent circuit tester like #PTW2993 going from almost…

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Answer 7

It should be getting close to 12 volts if the power output is set to the maximum on the brake controller. Some brake controllers will not work properly if they are titled or turned to the side or if it has a leveler knob that is not level. Check…

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Answer 8

First, do a visual inspection. You should make sure that the front of the magnet is not worn to the point where the interior copper windings are visible. Also, check the armature surface (inside rear of brake drum where magnet rides) is free of…

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Answer 9

I believe you almost solved the problem when you swapped the wiring, but in reality you needed to use 10 gauge wire like part #10-1-1 (sold by the foot). You are experiencing a voltage drop due to the long distance of wire that's not thick…

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Answer 10

If your current springs have 5 leaves then going to a 7 leaf spring will increase the height of the trailer a little and make the trailer more susceptible to sway. Regarding capacity if you go with springs rated higher than what is required it will…

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Answer 11

Thank you for purchasing from etrailer! You did a great job selecting compatible parts. When using Leaf Springs #e64SR with the #AP233 Equalizer Kit and the #H248 Hanger Kit, there should be 29-1/2" between the front and center hangers and…

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Answer 12

You will need the Red LED Trailer Clearance or Side Marker Light #328-K-52 or Amber LED Trailer Clearance or Side Marker Light #328-K-51 for your 2018 Forest River Sunseeker motorhome. These lenses have the same Top Command SAE-AP2-16 markings on the…

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Testing Trailer Brake Magnets When Brakes Are Not Working

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