Why Would Trailer Brakes be Locked Up when Towed with 2007 Nissan Frontier 7-Way
Updated 09/02/2025 | Published 06/27/2025
Question:
Hi I have a 2007 Nissan frontier that I ordered a brake controller and harness for. When I hook the trailer up the brake box on the trailer doesn’t charge and the brakes lock up as soon as I try and move the trailer. I’ve read that the blue and black wire for the plug are sometimes switched on frontiers. I checked the female end of the plug on the truck and the black wire is showing about 3V without the trailer connected and the blue wire is showing about 13V. I am thinking I need to switch the wires, but before I go cutting anything I am looking for advice if that is what needs to be done.
asked by: Shane G
Expert Reply:
Hey Shane, yes if the blue wire is showing 13 volts all the time that would be the problem with the brakes locking up so you would need to swap those circuits as right now your 12 volt accessory circuit is being ran to trailer brakes which is locking them up all the time.
Jameson C.
9/2/2025
Hey Shane, did swapping the wires solve the issue with your trailer brakes locking up? I'm asking because your experience could really help others facing the same problem with their Frontier.