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bryanmartin's avatar
bryanmartin
Explorer
Feb 16, 2016

7-way wiring help

Hello everyone. I have a 2008 Fleetwood Santa Fe pop-up camper. Last summer I smoked the brake controller wiring harness in my truck when I hooked the camper up to it. I have since replaced all necessary components in the truck, but I'm still having trouble with the trailer. As soon as I plug the 7-way connector in to the truck, the 30A auto-reset breaker starts clicking repeatedly and the brakes lock up. Also, there are no lights, including interior lights from the 12v system.

I've been trying to chase a short, and what I've found is that of the 6 wires that are part of my harness, all but two are grounded (i.e. have continuity to the chassis). Neither the Black nor the White are grounded, but the red, green, brown, and blue all are. Even with the battery disconnected. This doesn't seem right unless I'm missing something. Which should have continuity with ground and which should not? The wires all disappear into the frame after that, so they're very difficult to trace. Thoughts?

Thanks,
Bryan

7 Replies

  • Matt_Colie's avatar
    Matt_Colie
    Explorer II
    Feb 17, 2016
    Bryan,

    I hate to tell you that I fought a case like this once.
    I wish you luck as in my case the trailers main harness had taken a hit because of a manufacturing mistake that crushed the cable.

    If you are measuring things with a meter, a bulb may look a lot like a short. Start by taking all the bulbs out. (When you go to put them back, clean things and use di-electric grease.)

    Do you still have the shorts to ground that you had at the start?
    If yes, you have a real problem. Inspect the harness for as much of its run as you can. If you can't find the damage, try to borrow a "cable tracker". If you attach this to one of the shorted wires and follow the cable route, you should a serious serious loss of signal where the short exists.

    Be ready for a fight.....

    Matt
  • Artum_Snowbird's avatar
    Artum_Snowbird
    Explorer
    Feb 16, 2016
    If I was doing it (40 years experience) I would take your jumpers from the truck battery, through a fuse on the positive, and put one lead in the ground, and move the other lead around on the plug. You might find some things work, and others do not. If you blow the fuse when you do this, pull the bulbs out and try it again. If it still blows, you have either a plug mess (often they can short out) or a wiring fault that would involve more checking.
  • DougE's avatar
    DougE
    Explorer
    Feb 16, 2016
    All of the lighting circuits will have continuity to ground. There is resistance from the filament in the bulb, but you will still get an indication of ground continuity. An ohm meter would give you the actual resistance, but is not necessary for troubleshooting the wiring.
    K Charles is right for the first step. Check the TV output at the plug.
    I often use a spare battery to check the trailer circuits rather than hooking up to the TV. Since you may have a short I'd put a circuit breaker in the power circuit you set up to test with.
    etrailer has plug wiring diagrams if you're unsure of the proper orientation.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Feb 16, 2016
    You have a bunch of to-ground shorted wires. Suspect your pickups SOCKET where the wires connect to the reverse side. TAKE PHOTOS WITH YOUR PHONE!

    If the wires are still shorted when both ends are disconnected, you must replace the harness or dig out an air chisel and fish tape.

    Why the harness smoked is a mystery. The fuses protecting each individual wire should have come into play long before that...
  • enblethen's avatar
    enblethen
    Nomad
    Feb 16, 2016
    The ground you are seeing could be the lamps in the trailer.
    Blue should be the brakes
    Green should be right turn
    Brown should be taillights and marker lights
    White should be ground. trace it toward the rig. It should connect to the trailer battery ground. Normally spliced under the trailer behind the A frame portion.
    Black should be the battery positive from the TV and trailer battery. Trace it back to ward the rig's wiring. There should/could be a circuit breaker or damaged splices where the trailer battery connects to the umbilical cord from TV.
    You could use a short jumper wire from the trailer battery to each light function for testing.
  • K_Charles's avatar
    K_Charles
    Explorer
    Feb 16, 2016
    Unplug the TT then check the receptacle on the back of the truck. Is ground ground? Is the brake wire and the 12v wire in the right place?

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