Troubleshooting Low Voltage Coming From A Trailer Brake Controller

Updated 06/26/2024 | Published 06/12/2024

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Thetford Aqua-Magic Style Plus RV Toilet - Standard Height - Round Bowl - Slow Close - Bone Ceramic

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Digital Multimeter with 42" Long Test Leads - LED Display

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Question:

Do you know how much voltage a brake controller should put out to the magnets on a travel trailer? With the gain all the way up and pressing on the pedal, I have 4.2 volts. When sliding the bar over on the controller, I have about 9.2v

asked by: Robert W

Expert Reply:

Hey Robert,

The manual override settings differ for each brake controller but will typically send either full a 12 volts or up to a preset voltage. Brake controllers will typically also prevent you from sending full voltage back to the brakes by pressing the brake pedal unless you're moving at a specific minimum speed. Verifying the settings are correct on the brake controller is going to be the first step in troubleshooting.

The next step would be test the output wire at each connection point with a multimeter # PT89ZR to see where the voltage is dropping. If the distance is too great voltage will drop due to the resistance in the wire. Increasing the wire gauge can help reduce voltage drop. It's also important to have a good corrosion-free ground for the brake controller and brake magnets to operate properly .

What brake controller do you currently have?

expert reply by: Kevin C

Robert

6/26/2024

I have a Tekonsha Voyager

Jesse M.

6/26/2024

@Robert Did you adjust the inertia sensor on your Voyager # 39510 when you installed it? I would first make sure that it's calibrated so that the controller can accurately read and respond to how hard you press the brake pedal. I would also check the voltage on the black wire for the wire harness. This should be your 12v power coming into the brake controller. If you're not getting 12 volts here then there's an issue with the power. It also wouldn't hurt to check the white ground wire to make sure it's making good contact with an unpainted portion of metal.