My sister/SIL have a bumper pull and after they drug a bare spot in their wiring pig tail, & shorted it out I, for Father’s Day got the job to replace it. Before I did, I tried the plug in the pickup & just for drill checked for power at the pins. The Blue brake wire has power, that can’t be right….can it? I'm a motorhome person so know little of trailer operations.
so, im a motorhome person too, and know little about trailer wiring, but i would suspect the blue brake wire has power all the time, because it is a safety system, where the brakes are engaged if the power gets cut off. i could be wrong. --chris g.
I believe the blue is proportional VDC from the brake controller? I have never had a need to diagnose the 7 pin connectors other than general maintenance pin cleaning. Does the trailer have a brake away switch? I believe when the pin is pulled it puts full power on the trailer brakes, something to think about Good luck Mike
