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Calling all wiring wizards - Help with fisher MM1 - 2000 chevy light harness wiring

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

  1. alohazabel

    alohazabel Member
    Messages: 44

    I'm trying to wire light harness #26070 to my 2000 silverado 1500

    I'm looking at these instructions, and the wiring diagram on page 3:

    http://library.fisherplows.com/fisherplows/pdffiles/26116_110998.pdf

    My 9 pin truck side harness has two brown wires, how do I tell which is which?

    Where does the brown wire connect to the truck wiring?

    For the turn signal wires, what color truck wires and how do they connect to the truck wires?

    Can i just tap into the truck wires? Or do I actually have to cut and splice wires?

    I'm only using 4 relays, leaving out the DRL and Park Lamp relays, which I was told would work fine by the guy at the shop. Is this ok?

    Thanks.
     
  2. alohazabel

    alohazabel Member
    Messages: 44

    I have all the relays wired, just trying to figure out how to connect the three wires to my truck wiring

    - purple -turn signal

    -gray - turn signal

    -brown - park lamp
     
  3. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,972

    Cut and splice using heat shrink butt connectors
     
  4. alohazabel

    alohazabel Member
    Messages: 44

    positive wires?

    fora ll three of the lights, I tap into the positive wire, correct?

    my last question is about the two brown wires in the truck side harness. One goes to the relays, and the other to the parking lamp wire in the diagram

    Does it matter which brown wire goes where? or do they make a loop or something?
     
  5. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,972

    That I'm not sure of. Need to look at that on a bigger screen then my phone
     
  6. jb1390

    jb1390 Senior Member
    Messages: 710

    It does matter which one goes where, the brown wires should originate (I think) from different harnesses. Hook up to the corresponding spot on the relay (brown wire from plug to plow hooks to 87 on relay) (brown wire that is tapped into vehicle wiring hooks to 86 on relay). If you are unsure which wire is which, you can test that using a multimeter set to measure ohms.
     
  7. jb1390

    jb1390 Senior Member
    Messages: 710

    When I "tee" into an existing wire, I strip back the insulation for about an inch using a utility knife/wire strippers. I wrap the wire around, solder it, and tape (or heat shrink if possible) over the joint. All my joints are soldered whenever possible, you will never get corrosion on the inside of the soldered joint.

    You can also do it using butt connectors, but I have had some problems with crimp reliability, especially using those cheap crimping tools they sell at box stores. Crimps are way faster than soldering though, but not worth it for me, I like the increased reliability I get with soldered joints, especially in a corrosive environment.
     
  8. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,972

    To each his own. Not feasible for me to solder at all. But go with what works
     
  9. jb1390

    jb1390 Senior Member
    Messages: 710

    A 50 watt temperature controlled iron is really nice to have, a cheap 20 watter from wal mart doesn't really cut it once you get to any decent size wire, the wire wicks away too much heat.

    The worst thing for reliability are those stupid quick splice pieces, that just cut through the insulation. A butt crimp splice is 1000 times better than that.
     
  10. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,972

    Oh I have stories and pics of them stupid scotch locks. Pos they are
     
  11. alohazabel

    alohazabel Member
    Messages: 44

    still stumped

    When plow is disconnected, truck lights work

    When I connect plow, truck lights click off, but plow lights don't come on, and there is no power at the # 87 terminal on the plow light relays

    this is how I have the 4 relays wired:


    Truck Low:
    85- black/orange (ground)
    86- brown from harness (+)
    87- jumper to PLOW LOW 86
    87a- orange to lights
    30- yellow to lights

    Truck High:
    85- black/orange (ground)
    86- brown from harness (+)
    87- jumper to PLOW HIGH 86
    87a- red to lights
    30- green to lights

    Plow Low:
    85- pink from lights
    86- jumper from TRUCK LOW 87
    87- Black - Harness
    87a- Empty
    30- Red from batt(+)

    Plow High:
    85- pink from lights
    86- jumper from TRUCK HIGH 87
    87- White -Harness
    87a- Empty
    30- Red from batt(+)

    -I spliced the other brown wire from the harness into the marker light (+) wire on truck drivers side (brown wire)
    -I haven't hooked up the purple or gray for the turn signals yet

    I checked the Plow Low and Plow High #87 terminals with a test light while I had the plow connected, and there was no power, so no power going out to the plow lights, 87A had power on both relays

    The weird thing was that there was power at the 85 terminal with the pink wires, which I thought should be a ground

    Any Insight? I'm stumped.
     
  12. jb1390

    jb1390 Senior Member
    Messages: 710

    Let me see if I can walk through this.....thinking/looking as I type.

    87a is normally closed, so you will have power there assuming power into the relay, which you said you have. Doesn't matter as it's not connected to anything.

    You have power in to pin 30 on both plow relays correct?

    When you plug plow in, do you get +12v to 86 on plow high beam and plow low beam relays?

    If you do, see what happens when you ground pin 85 instead of tying it to the pink wire. I bet based on what you are describing, everything will work correctly.
     
  13. alohazabel

    alohazabel Member
    Messages: 44

    yes.

    you're right. terminal 87 lit up and the plow lights came on when i put a wire from the negative battery terminal to 85 on the plow low and the plow high relays.

    so is my problem with the pink wire? or a bad connection somewhere?
     
  14. jb1390

    jb1390 Senior Member
    Messages: 710

    I think the wiring diagram is wrong. If all works correctly, tie that wire to ground and call it a day.
     
  15. alohazabel

    alohazabel Member
    Messages: 44

    great

    thanks for your help. I was jacking with those wires all day, scouring the internet, talked to three different fisher dealers on the phone, and couldn't get it licked.

    i tried it again just to make sure that everything works, and it does. I'm going to leave it just like you said, and not touch it again unless the lights stop working.

    thanks again for your help. you just freed up my weekend.