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Ultramount electrical problem

Discussion in 'Western Plows Discussion' started by atom1013, Nov 6, 2012.

  1. atom1013

    atom1013 Junior Member
    Messages: 16

    Have a question my truck headlights are not flipping over to the plow headlights when I plug in all 3 plugs. I just wired my 2011 gmc and had it working so i thought. Then I realized I had one high beam plug flipped around so I tried to fix that and when I hooked up the plow now the headlights done come on the plow. Everything else works fine just that my truck lights stay on and the plow light are off. I pinched the plow end of the 11 pin harness between the truck and the plow but it appeared to be fine , I am thinking that's probably the cause but like I aid everything else works when I plug it in. Thanks
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The headlamps are switched via a ground feed from the plow back to Iso module through the 11 pin harness. This is how the Iso knows you plugged the plow in and knows to switch the lights over to it. So I'd be akin to believe you did in fact cut a wire in the 11-pin as long as everything is good in the wiring on the plow side, ie it didn't have an existing issue.

    Look for a cut black/orange wire.
  3. atom1013

    atom1013 Junior Member
    Messages: 16

    Ok thanks I am going to check that out now thanks
  4. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    You say your plow works but the lights just don't come on plow side? If you pinched that ground wire then the lights would not switch off on the truck and the plow would not work either. If you just installed this system on a GMC I expect you have your original truck headlight plugs flipped over where they plug into the Western headlight harness. These plugs will plug in two ways, if you have it wrong the truck lights will work but the plow lights will not. As much of a pain in the butt it can be, try pulling a headlight and flipping the original headlight plugs over and plug them back in again to the Western headlight harness. Sounds to me like you have all four flipped the wrong way. You do have four headlamps on the truck right?

    That ground wire that B&B is talking about goes from the isolation module out to the plow headlamp plug, goes through and then flips right back around coming back to the truck and then to ground through two quick disconnects and then finally to ground at the battery negative terminal. If that wire was open the controller would not light up, the truck headlights would stay on and the plow would be dead.