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plow lights wont switch over

Discussion in 'Western Plows Discussion' started by littleman, Dec 13, 2013.

  1. littleman

    littleman Junior Member
    Messages: 5

    04 f350 v10 with a western unltramount plow. i can not get the lights to switch from the truck to the plow. the truck lights stay on but the plow lights will not go on high or low or running lights. plow turn signals do work however. i have re placed the 2 relays with brand new ones. i have checked all the ground wires too. but on the relays if you run a wire from 30 to 87 the lights will come on. just depends what lights come on depending witch relay you are jumping(high or low beam relay). at this pont i am completly stumped and dont know what to do. the plow its self works fine too. up down left right. it all worked when i put it in the back of the shop this past season. any help is apprciated. thank you.
  2. mishnick

    mishnick 2000 Club Member
    Messages: 2,353

    Sounds like you are talking about uni-mount with the relay headlight switching system. The control wire can be hooked up with no relays at all and the plow functions will all work. The signals and markers should also work because these systems are simply wired in parallel. I would be checking the marker light wire feed to the relays. As I recall in this system it's the power from the marker that activates the plow / truck switchover function. Look at where your relays are, left or right side. Then pull the signal / marker lamp from the same side. There will be two wires tied into the wires coming from that lamp. The third wire will not be tapped, it is the common ground. Determine which of these two wires is the marker and then verify that power is getting from the original vehicle harness to the Western relay control harness. I suspect you may have one of those cheap crap fold over connectors that inevitably fail. From there check that wire where it connects to the relays and make sure power is not interrupted. That's where you should start and probably where you will finish too, good hunting...