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Tach installation

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by FL84K5, Jun 7, 2002.

  1. FL84K5

    FL84K5 1/2 ton status

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    The Autogage tach I ordered just came in. The instructions say to hook one of the wires up to the negative on the coil. How do I do that on a stock 84 Blazer? It also says to hook a wire into the 12 volt ignition switch and another into the 12V dash lighting. How do I hook these up? Does my truck have an electronic ignition? If it does the instructions say to hook the wire to the tach terminal on the elctronic igntion. Where is that located and how do I hook up all the wires to it? You can probably tell I don't have much mecanical skills, but I gotta start somewhere.
     
  2. sosamantx

    sosamantx 1/2 ton status

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    they should all basically be the same (color of wires etc. ) see if this helps (page 3 is a pic). as for your 12V source just find one that is hot when the key is on, you could probably just hook it up to your fuse box if you don't want to splice it in. and as for the dash lighting, you'll have to probe on the back side of the headlight/dimmer switch. i think i had just wired mine to a 12V source (so of course it won't dim). but, i'd go with what your instructions say, just use this as a reference!! /forums/images/icons/wink.gif

    www.autometer.com/hp/instruction_download/instructions/192r.pdf
     
  3. m j

    m j 1/2 ton status

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    if it is HEI distributor it has a terminal marked TACH.
    unsure if you truck has HEI or a computer controlled distributor
     
  4. FL84K5

    FL84K5 1/2 ton status

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    ok, i see the tach terminal. how do i hook the wire up to it and the light switch?
     
  5. creampuff90k5

    creampuff90k5 1/2 ton status

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    On an HEI, the "tach" terminal should accept a male blade terminal available from auto parts stores and radio shack. As far as the tach lighting goes, you are going to have to access the wiring that comes off of the headlight pull switch. If you don't want to go through the trouble of finding the "dimming wire", you can splice into any of wires that become 12V+ when the switch is turned on. Either way, this will require buying or borrowing a test light unless you're a real good guesser! One of those blue "scotch lock" connectors would be a good way to make this splice.
     
  6. Impex

    Impex 1/2 ton status

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    to connect it to the coil marked tach i used a female solderless connection and crimped that to the end of the wire and then it just slides on the end of the coil marked Tach. as for the light i did the same thing as sosamantx /forums/images/icons/wink.gif
     
  7. Blue85

    Blue85 Troll Premium Member

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    If you want a "no-brainer" approach to wiring in the light, just look for the wiring that goes to the transfer case shifter or for the lighting of the radio. The wire should be either brown or grey. The radio lighting is on it's own harness, seperate from the other connectors. And it is nicer to have it work with all of the other gauge lights than just being on all the time.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    If it were me I'd find an 80's Camaro in a wrecking yard and cut the tach plug that goes to the distributor, and solder that to the tachs distributor lead.
     
  9. Michael

    Michael 1/2 ton status

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    A .250 Female spade connector crimped onto your wire will work great on the "Tach" terminal....or a Camaro one....
     

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