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1 dim plow light

Discussion in 'Western Plows Discussion' started by jlb54, Dec 9, 2014.

  1. jlb54

    jlb54 Junior Member
    from Ripon
    Messages: 2

    I have a 8.5 foot ultramount with a 3 wire hookup and 4 port module ( green tag) Since the first hook up this year the passenger side headlight has not worked plow side. Truck lights work fine. After checking all connections by cleaning and reconnecting I now have right side headlight working but it is very dim only a little over 8 volts. I got the headlight to come on dimly after cleaning the 11 pin plug. Double checked grounds,and no luck. Replaced module with used one bought on ebay. Same results, still dim. I switched plug 3&4 on the module and right side stayed dim. Plow functions all work fine. Lights worked fine in past years but not now. I am thinking my problem might be the truck side plug because that is where I found I had power truck side and and not plow side, like I said after good cleaning I got a dim light. I am going crazy trying to figure this out.
  2. SullivanSeptic

    SullivanSeptic PlowSite Veteran
    Messages: 3,422

    I actually had the same problem on a wideout, but I can't remember what I did to fix it. Worked on so many things last year, they all blur together. But it is obviously an electrical issue. Possibly Iso module that i replaced that fixed it.
  3. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,391

    I would start at the Iso IN from the trk lights. See if your getting 12v in. Then I would Ck power out of the Iso, then at the grill plug.
    Side note....the harnesses are rather, cheapish,,,,they get cuts and corrode rather easily so Ck around sharp objects
  4. mishnick

    mishnick 2000 Club Member
    Messages: 2,353

    You swapped the two input plugs on the iso module and the same side light still runs dim. You tried another module and no change. That leaves the wire from the module to the grill and then from the plug to the headlight. My money is on the cable from module to grill plug. Its an IR drop (bad connection) That is, a voltage drop when current is flowing through a resistance. Just like water in a hose, if you stand on a hose when no water is flowing the pressure will remain the same on both sides of the restriction. But if you start letting water out of the end then the pressure on outlet side of the restriction will drop because the water can't get through fast enough to maintain it. Electricity works the same way.

    Look at the 11 pin grill plug. Check the pins and then look at the wire immediately behind the plug. You could try bending the wire there when the plow lights are on. These harnesses frequently get damaged just behind the plug, the wire breaks and you get the make and break connection. Most times its on the truck side but look at both.
  5. jlb54

    jlb54 Junior Member
    from Ripon
    Messages: 2

    Want to thank you for the reply's. Did some more voltage checks and found a drop of about 8 volts at the 11 pin connector on the blue orange wire. Replaced harness from module to plow and now have full power. Thanks again:mechanic:
  6. DManning

    DManning Junior Member
    Messages: 1


    jlb, would you be able to post pictures pointing and showing what exactly you did and replaced. I have the same issue, was dim late last winter and now it out completely. I swapped in a new headlight and still dim.
  7. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,391

    The truckside harness. The 11 pin connector all the way you the Iso module.