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03 to 02 2500HD harness convert

Discussion in 'Western Plows Discussion' started by stevesmowing, Aug 22, 2007.

  1. stevesmowing

    stevesmowing Member
    Messages: 78

    I am trying to convert and 03 2500HD wiring harness to a 02 2500HD wiring harness. I already switched the relay wiring so it matches the 02 but it still does not work right. Do I have to change any pins on the connectors that plug into the head lights or the plow plug? Both harnesses (truck and plow halves) are the 12 pin style.

    Right now with everything plugged together both the high and low beam lights come on together on the truck. The only thing that will work on the plow are the turn signals.
  2. OneBadDodge06

    OneBadDodge06 Senior Member
    from Iowa
    Messages: 770

    I had the same exact problem. I'm guessing this is a unimount setup (relays)..but you cannot convert an 03-04 harness to the 02 style. It is completely different. But I have an 02 harness for sale if you're interested.

    The problem is that not all the jumper wires and such will not allow the headlights to switch on.....and the only way to do it is with a different harness.
  3. stevesmowing

    stevesmowing Member
    Messages: 78

    I was able to convert the harness. I had to switch 16 pins in all. on each side there are two long black connectors with male pins, I had to switch those, I also switched the pins that plug in from the western harness to the head lights. I also re-wired the relays. It works great now!.
  4. Philbilly2

    Philbilly2 PlowSite Veteran
    Messages: 3,794

    The 02 and earlier headlights have only 2 pins for a connection. The o3 and later models have 3 pins. I have never heard of a 03 uni-mount harness for a Chevy. I have always been told that you have to use the ultra-mount isolation harness. I made a seperate headlight control for my truck because I am way to cheap to buy that isolation harness.