Should The Trailer Brake Circuit Have Continuity Between the Blue Power Wire and Ground?
Updated 06/09/2024 | Published 03/17/2023
Question:
I have continuity between my ground pin and brake controller pin on the trailer side of the system. The breakaway battery is disconnected, but I appear to have a short to ground on my blue wire pin to the white wire pin. The harness is disconnected from the vehicle. Should there be continuity there? The breakaway plunger is still ed in the breakaway socket. I assume the plunger being removed would only cause continuity between the aux 12v power pin and the break controller blue wire pin, as that is its function.
asked by: James M
Helpful Expert Reply:
It is normal to have continuity between the brake(blue) wire and ground(white) wire. The electric trailer brake is an electromagnet when it has power it attracts to the steel inside the hub/drum. If you are having issues with your trailer brakes please read the article I linked below as it will run you through the process of testing the magnets.
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Wes
6/3/2024
In the process of testing my magnets, wiring, etc. I tested for ohms on my 2017 F150 7 way and get a reading between the ground and the blue brake wire. The trailer is not connected. Should there be continuity between these two wires on the truck side with the truck unplugged from the trailer and the truck is not running? This all started as I get 13.3 volts out of 7 way plug but when I test on trailer side at the pin box it drops to 11.6. The magnets all test good for their ohms but when I test them for amps the one is at 2.5 amps but I think it is low cause it is not getting 13.3 volts. Just trying to rule out the truck side. If there is supposed to be some ohms between the ground and brake wire pins coming out of F150 plug then at least I can rule that out.