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Western Unimount Lighting problem

Discussion in 'Truck & Equipment Repair' started by mjcp, Feb 13, 2012.

  1. mjcp

    mjcp Junior Member
    Messages: 24

    95 F-150 Unimount 9 pin harness

    System was running fine for years (Original wiring config=good)
    No snow yet this year so no night time plowing.

    Yesterday I noticed my lights were all out (except for PS lower Parking light).
    Truck lights are on. Doubt that all bulbs blew at once so I suspect wiring, but I wonder if there is a quick way to troubleshoot, before I pull out the schematics and try to learn enough to build a rocket ship.

    Thanks in advance
    Mike
     
    Last edited: Feb 13, 2012
  2. RTE Todd

    RTE Todd Junior Member
    Messages: 4

    There should be a brown wire and a grey wire connected to your vehicle's driver-side marker light. Test for power on the brown wire (should be tapped into vehicle's marker/parking light circuit). This wire provides power to the (2) relays, which are used to transfer the lighting from the truck to the plow. Also, check you 9-pin connectors to make sure there is no corrosion or bent/broken pins.
     
  3. RTE Todd

    RTE Todd Junior Member
    Messages: 4

    FYI: the grey wire should be tapped into the driver-side turn signal. Do the turn signals work? How about the high beams?
     
  4. RTE Todd

    RTE Todd Junior Member
    Messages: 4

    FYI, the grey wire should be tapped into the vehicle's driver-side turn signal. Do the turn signals work on the blade? How about the high-beams?
     
  5. mjcp

    mjcp Junior Member
    Messages: 24

    Update

    Thanks for the quick reply,
    I never thought to check the high beams, Yes they work. so
    High beams work - Low beams do not.
    Passenger side turn signal works in both high and low beam
    Drivers side turn signal does not work in either High or Low Beam
    Running lamp only lights on passenger side in both high and low

    Note: I never checked turn signals or running lights in the past - I can't rule out the bulbs.
    Once I find where I packed my meter I'll start tracing some electrons.
    Thanks again
     
  6. RTE Todd

    RTE Todd Junior Member
    Messages: 4

    Because your high-beams work, I would say that one of your relays is bad. One relay handles the low beams, the other handles the high beams. The low beam relay should have the following wires attached to it:

    Black
    Brown
    Orange
    Yellow
    Black w/ orange stripe
     
  7. mjcp

    mjcp Junior Member
    Messages: 24

    That was my first thought after looking at the schematic.
    Thanks I'll track it down tomorrow.
    Appreciate your responding to my problem
    Mike
     
  8. mjcp

    mjcp Junior Member
    Messages: 24

    Update - Running Lights and turn signal where bad bulbs. 4 new bulbs and a bad cut on my thumb, and now it's just the low beams not working. Betting on the relay since vehicle lights stay on so I've ordered the relay. Even if I'm wrong I won't mind having a new relay in there. I'll keep you posted.
     
  9. mjcp

    mjcp Junior Member
    Messages: 24

    Final update- replaced both relays with Bosch 5 pin relays from Autozone (lifetime warranty).
    One relay was badly corroded and the case was bursting on top. Everything works great now. I will wait for a nicer day then clean the connectors better and coat the terminals with dielectric.
    Thanks for the help - people on this forum are a terrific resource!