Electric brake wiring

Old 03-28-19, 06:05 PM
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Electric brake wiring

I am wiring a new 7 pin male plug with a pre-connected pigtail to a lowboy trailer. All of the trailer lighting is working fine. There are two more wires on the trailer side, a black and white that I assume are for electric brakes. On the plug pigtail, according to the wiring diagram there is a 12 ga blue wire for trailer brakes. I need to know which wire the blue wire connects to, the white or black, assuming the other one goes to ground. The 7 pin connector uses white as a ground so my gut instinct says blue to black and use the white wire to ground. Is that correct?

Old 03-29-19, 05:22 AM
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There is no standardization of colors. Look online at the wiring diagrams and you'll see colors all over the place. The only way to know where your wires go is to crawl under the trailer and look.
Old 03-29-19, 05:32 AM
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Verify white and black wires (trailer side) go to the electric brakes. Verify resistance between white and black wires is less than 10 ohms. Measure twice, reversing meter leads between measurements. If one reading is less than 10 ohms and the other is near infinity, there is a diode in the wiring to prevent reverse voltage application. The wire connected to the positive probe (when reading less than 10 ohms) is where the 12 vdc gets connected. If both readings were less than 10 ohms I would proceed as follows since proper solenoid operation is polarity sensitive.. Jack up one wheel of trailer and verify tire spins. Connect 12 vdc battery terminals to black and white wires. If tire won't spin, this is the polarity for your source. If tire spins, reverse battery connections. Tire should not spin.This is the polarity for your source.
Old 03-29-19, 06:57 AM
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