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One headlight ??

Discussion in 'Western Plows Discussion' started by caddytruck89, Dec 9, 2009.

  1. caddytruck89

    caddytruck89 Senior Member
    Messages: 157

    Quick one. Just finished an install on 04 gmc 3/4 ton. low beam on driver side is fine. Low beam on passenger is light very dim. I mean like a candle. Both high beams work great. Tried swapping bulbs no luck. Seems like a ground issue?? But why the high beams?? It's a 3 port isolation module. Ultra mount pro.
  2. Steve000

    Steve000 Junior Member
    Messages: 10

    I just installed the same plow/iso. mod. set up on a Ford Super duty and had a similar problem. The drivers side low beam wouldnt work on the truck or the plow but the high beams worked fine. The dealer i bought the wire harness from said some trucks may need a "configuration plug" which mine did. I plugged it in and the lights worked fine. The connector is located on the harness that plugs in to port 1 about 12" from the isolation module. If you cant get this plug i guess you could just splice the wires together depending on your set up. I dont know if this is the problem your having or not but hope it helps. Someone who knows more than me will likely chime in soon with a better response haha

  3. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,039

    The GM reverses it's positive / negitive common by reversing the headlight connector. Notice where the ISO Module's light harness plugs in to your actual trucks headlight harness. The connectors are labeled A & B, simply reverse the way they are plugged in and it will correct your problem. The Ford does this by the configuration plug.....to my understanding GM DOES NOT.
    Last edited: Dec 10, 2009