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Alternating Headlight Beams

Discussion in 'Truck & Equipment Repair' started by GETSOME!, May 6, 2014.


    GETSOME! Junior Member
    Messages: 27

    I have a '98 Dodge 3500 that I use for my plow truck. I've been going through it making some repairs etc. One of my repairs was to replace the headlights since the lenses were cloudy beyond restoring. Well when I went to make sure they were adjusted properly, I realized a very strange issue. When on 'low beams', the driver's side projects the low beam and the passenger side is much brighter, as if the high beam is activated. If I hit the switch on the steering column to the 'high beam' setting, the driver's side high beam comes on but the passenger side goes to low beam.

    I didn't do much investigating, but it seems like there is a wire or two reversed somewhere. Or maybe this has something to do with the Isolation Module for my Western MVP Plus plow???? I did a quick swap of the #3 & #4 plugs on the 4 plug isolation module, but that didn't solve anything. Anyone have this happen before or can anyone suggest where I should begin?
  2. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    did you do anything with the wiring when you were working on the lights? sounds like you crossed wires somewhere.

    GETSOME! Junior Member
    Messages: 27

    No, the bulbs are simply plug and play. I think this may have been an issue before I changed the HL housings. Its just that the old HLs were soooo fogged that I could never tell. Seriously, I think that a birthday cake candle put out more like than those old headlights did!
  4. info4tim

    info4tim Senior Member
    Messages: 235

    Bad ground

    GETSOME! Junior Member
    Messages: 27

    I forgot to add an update that I had figured out the problem. There are 3 wires that go to each headlight, hit beam power, low beam power, and ground. Well it turns out that the high and low beam power wires were switched and in the wrong spots in the pigtail plug that came with my Western plow. I'm not sure if it came wired wrong from Western, or if it was a mistake on the part of the Western dealer I had install the plow on the truck.
    Regardless of where the blame falls, I was able to troubleshoot it with a multimeter. I simply cut the misplaced wires, switched them, and reconnected with heat shrink butt connectors. Problem solved!