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Lights won't switch from truck to plow

Discussion in 'Western Plows Discussion' started by tim975, Nov 22, 2007.

  1. tim975

    tim975 Senior Member
    Messages: 103

    Hey guys, Happy Thanksgiving! I'm having problems with my dad's truck, a 2000 Chevy Silverado 2500, with a Western Unimount. We hooked the plow to the truck, and the plow works just fine, but the headlights won't switch from the truck to the plow, no lights at all on the plow side. All the lights on the truck work fine as well. Any suggestions? I checked what fuses we could find on the wiring, they look fine. Maybe a relay? Any help is greatly appreciated.
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Not even turn signals on the plow?
    Does the truck have the extra Western supplied DRL module under the hood? (did the DRL's work with the plow headlights?)

    If you don't even have turn signals, then there's no ground on the plow side of the light harness.

    Make sure the pins are clean and in good shape in the grill connector.
  3. tim975

    tim975 Senior Member
    Messages: 103

    Hey B&B, I went thru and cleaned the plugs again in the grill, in case I missed something. Still no luck. No turn signals neither, and yes, the truck has the DRL module under the hood, by the brake fluid reservior. Got me, everything worked fine at the end of last season. I'll check it out again tomorrow, too dark out.
  4. schuitb

    schuitb Member
    Messages: 95

    I have same thing!

    I have the same problem.. but my turn signals work fine... I tried cleaning and wiggleing the conections but nothing changed... If someone else had the same thing before let me know..
    2003 western 7.5 uni.

    Thanks Brian
  5. Philbilly2

    Philbilly2 PlowSite Veteran
    Messages: 3,793

  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Definitely sounds like a ground problem then.

    Check the black/orange wire where it connects to the neg battery cable on the pump motor. Make sure it's clean and tight and not broken off. I'd actually check for ground with a test light at one of the lights also..

    The plow will function if this wire is broken or disconnected but none of the lights will work.
  7. Garagekeeper

    Garagekeeper Senior Member
    Messages: 459

    You need to check and see if you are getting power to either terminal # 85 or #86 on the relays when you turn on your park lights. The relay gets its power from a wire tap off your parking light, if the connector is corroded you will lose all headlight and park lights on the plow. The ground that causes the relays to operate comes "from" the plow when you plug the multi pin connect in, if your not then you need to check the wiring from the ground off the motor back into your harness.
    :rolleyes: John...
  8. I have something similar, my lights switch on but not my park lights on my ultra mount night hawk lights. I added them last year and they did work last year but this season they havent. The turn lights work but not the park lights. Any thoughts? Im going to check the grounds like you guys have said above. I also do have a ISO plug thingy.
    Its on a F250.
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Check the brown wire in port # 3 on the Iso module with a test light. You should have power there with the park lights on.

    If you have power there, check the # 10 pin in the grill connector to see if it has power with the park lights on.

    If it does, then it's something on the plow side of the harness.. keep following the wire up to the lights, checking for a poor connection with the test light.
  10. traviswalker007

    traviswalker007 Senior Member
    Messages: 188

    same prob

    I had the same problem last week and a fleer on here helped me out alot...check the power wire to the low beam relay, and check power supply to high beam relay, my power wire was broke..