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No headlights, signal light flashes all park lights, brake cuts everything

Discussion in 'Western Plows Discussion' started by jemsegfarmer, Jan 10, 2012.

  1. jemsegfarmer

    jemsegfarmer Junior Member
    Messages: 3

    I have a Western Unimount MVP on my 2005 Fuso Fg 140. Everything was working fine and I went out in the morning and found the brake lights on. Headlights do not work on either the truck or plow. Brake and left signal affect all other lights incuding DRL.

    Am I looking at a bad ISO module? The brake thing seems a bit incongruent with that, but maybe they are working through the tail lamps.
    I don't have a Western dealer near here so I am on my own and need to figure this out pronto.

    I am going to try to isolate the ISO module and get my truck lights running as I need it for non plowing uses everyday.

    Any insights or advice would be welcome.
  2. jemsegfarmer

    jemsegfarmer Junior Member
    Messages: 3

    correction Ultramount, not unimount

    I have an ultramount, not unimount, if that makes a difference.
  3. Sharpcut 1

    Sharpcut 1 Senior Member
    Messages: 386

    Do you have an electrical connector for a trailer?? if you do, see if you have salt in the connector, bridging the gap. I have seen the salt conduct electric between the running light circuit and stop light, backfeed and cause problems. Them running light wire is the trigger on your relays for your headlights, so if it's going to ground somewhere, it will cause problems. Are all your running lights working on truck and plow??
  4. mishnick

    mishnick 2000 Club Member
    Messages: 2,353

    Sounds to me like this has nothing to do with the plow wiring but you could pull the headlights and then unplug the Western harness from the headlamps and plug the factory wires back on the bulbs. That would eliminate the isolation module from the system just to be sure. There are still three more wires connected to your truck, left and right signals and the marker light tap but they are connected in simple parallel so I can't see how they could be causing your problems. Checking that trailer plug is a good idea and have a look at the wires from the tlr plug up under the rear end to see if something has been damaged there. Perhaps a branch or something has jammed up in there shorting out your wires.
  5. jemsegfarmer

    jemsegfarmer Junior Member
    Messages: 3

    Good call !

    The trailer wiring it was. I had suspected that also after looking at it yesterday and had picked up a new connector on my way home. Your advice helped me get started with that though instead of wasting my time chasing other things. I think these trucks have the relay for the headlights and the brake lights on the ground side, so there was probably voltage going everywhere. I also found the connectors on the positive fuseboxe wires to the completely corroded away at the battery terminal....It is a wonder anything was working, it certainly wouldn't have for much longer.
    Back on the road again. Thanks for the help:)
  6. to_buy

    to_buy Senior Member
    Messages: 278

    A Fuso argh