1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Truck and plow lights on at same time

Discussion in 'Truck & Equipment Repair' started by mattpiotrowski, Dec 19, 2013.

  1. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    Hello All, Hopefully somebody can help me here. I have a newer Western Uni mount on my 86 GMC 2500. it has the 9 pin, 2 relay wiring harness. when i plug my plow in both my truck lights and plow lights are on. I know on westerns when you plug in the lights it switches one to the other. I replaced both relays with napa(192d) 87a relays and that still did not solve the problem. should the wiring harness be grounded anywhere? Any information is appreciated Thanks

    i forgot to mentioned that it seems like after the truck gets warmed up with the plow on the lights start to flash like they are trying to switch over. if i unplug the head light harness to the truck light harness under the hood it acts fine for a while and does it again and sometimes it will be fine all night

    my truck.jpg
     
    Last edited: Dec 19, 2013
  2. 2006Sierra1500

    2006Sierra1500 PlowSite.com Addict
    Messages: 1,758

    Is the extra light really a bad thing?
     
  3. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    No its not. Im sorry i forgot to mentioned that it seems like after the truck gets warmed up with the plow on the lights start to flash like they are trying to switch over. if i unplug the head light harness to the truck light harness under the hood it acts fine for a while and does it again and sometimes it will be fine all night
     
  4. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Well you said you got the 87a relays. Did you put the pins back in the same way and on the same relay number as per westerns wiring diag?
     
  5. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    Yessir, I went to Westerns website and got a diagram what wire goes to what prong on the relay prior to disconnecting
     
  6. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Well test light time. Start cking the wires to see what you have and don't have. Start with the gnd wire first. The blk/og one. With plow hooked up it sends gnd signal to the relays and the contacts close sending pwr to pin 87 out to the plow lights
     
  7. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    ok. does that ground tie into the same black-orange wire that goes to the selonid? i have the tower style one and the 2 small prongs one wire is black/red(i belive) and the other is black/og. should there be a jumper wire type that goes from any of those wires to the ground on the battery?
     
  8. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    No its ground comes from the blk/og on the plow motor the relays that is
     
  9. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    Ok. i get what your saying so the ground goes to the motor on the plow side (pump motor). But just out of curiosity, what would ground the harness for the lights when the plow is not on the truck?
     
  10. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Nothing. That's what the pin 87a is for. It goes pin 86 to 87a. When you gnd out the relst it goes pun 86 to pin 86 and plow lights ate lit
     
  11. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    ok. so what pins should have power when i hook the plow lights up
     
  12. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Ok. Gimmie a min and ill look it up
     
  13. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    ok. can you send the link also? thanks
     
  14. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Western plows .com. libary. And 3 and 4 port and relay wiring.
    Without plow
    Pin 30 yel to pin 87a org
    Pin 86 brn is parking

    Plow hooked up.
    Pin 85 blk/og gets gnded
    Pin 30 yel sends pwr to pin 87 blk out to plow
     
  15. Fixx

    Fixx Junior Member
    Messages: 3

    check the brown wire feeding all the releys,,it they dont have power from the parking lights all the lights will come on...or the plow plug is not completeing a ground to turn off the truck lightd..
     
  16. mattpiotrowski

    mattpiotrowski Junior Member
    Messages: 26

    I Checked all the wires and have power going to the ones that should have power to them when lights are activated. I put a jumper wire from the ground straight to the negative to the battery and still have nothing.
     
  17. Fixx

    Fixx Junior Member
    Messages: 3

    that is the most commn problems i see,,if the parking lights are not worklng on yhe plow then iys the brown wire that goes ti fire all releys.
     
  18. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    What gnd wire? The blk/og at the relay?
     
  19. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,991

    Are you 100% sure you got the right relays. Sometimes the 87a (5pin relays ) have a jumper for 87 and 87a to be active at the same time.
    With plow hooked up. Test light both 87 and 87a pins to see if you have pwr at both