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tachometer installation

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by joshkbomb, Jul 17, 2004.

  1. joshkbomb

    joshkbomb 1/2 ton status

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    I recently acquired a tachometer out of a firebird and would like to try and put it in place of that huge gas gauge. The back of the tach has three screws labeled coil, 12v, and ground. My question is, how do I connect this thing and what gauge of wire should I buy? I can do ground, but exactly how I should get the 12v and coil hooked up I don't know. /forums/images/graemlins/1zhelp.gif It's an '87 Blazer 350.
    thanks /forums/images/graemlins/grin.gif
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    The 87 should be a remote coil. So you need to hook up to one of the leads from the top of the coil. I don't remember which one it is but it someone should. If they don't I can check my truck in the morning and tell you.

    The 12v wire should run to a keyed ignition source wire. Anything that only gets power when the key is one should be fine. wire size shouldn't be to heavy. 14 gauge ought to do just fine.

    Harley
     
  3. jjlaughner

    jjlaughner 3/4 ton status

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    [ QUOTE ]
    The 87 should be a remote coil. So you need to hook up to one of the leads from the top of the coil. I don't remember which one it is but it someone should. If they don't I can check my truck in the morning and tell you.

    The 12v wire should run to a keyed ignition source wire. Anything that only gets power when the key is one should be fine. wire size shouldn't be to heavy. 14 gauge ought to do just fine.

    Harley

    [/ QUOTE ]

    Like this connector?
    [​IMG] /forums/images/graemlins/grin.gif

    I hooked my 12v under the out side of the radio fuse and my ground goes to a ground block on the firewall I made. /forums/images/graemlins/waytogo.gif

    Post up pics of the tach once you get it in /forums/images/graemlins/waytogo.gif
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    For your 12V ignition source, use one of these:
    Truck fuse panel 1

    truck fuse panel 2

    Page is dead now, should be back up tomorrow, too much traffic for the day. (no idea why that happened)

    Anyways, that jumble of plugs at the top of the fuse panel is where you will want to draw your power from. Figure out which is 12V ignition (easy with test light or voltmeter) and get the right connector (all are keyed) from a wrecking yard GM vehicle. (car or truck from 80's to maybe early 90's)

    Solder the tach lead to the fuse panel connector, and you are in business. This will keep you from having ANY intermittent connection issues, and allows you to easily remove the wire at a later time for any reason, without cutting.

    I can look up which ones are 12V ignition for you (out of the '87 electrical manual) but you'd still want to double check with a light or meter, so no real reason to consult the manual.
     
  5. BlazerGuy

    BlazerGuy 3/4 ton status

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  6. joshkbomb

    joshkbomb 1/2 ton status

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    I finally have everything hooked up and the tach and new gas gauge work, sort of. A couple resistors on the tach are getting really hot and a connection actually burned out. I fixed it and measured the voltage and it reads at 15V. The whole fuse block is at 15V when running and 14V when off. Is it supposed to be this way? I have the tach grounded on a screw in the firewall and the 12V lead to the radio connection.
     
  7. joshkbomb

    joshkbomb 1/2 ton status

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    Thanks for the info and pics. I found a screw in the firewall 6 inches to the left of the ones in your pic and used that one.
     
  8. joshkbomb

    joshkbomb 1/2 ton status

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    Thanks for the info. The links still don't work, but I'll keep trying. I tested all the plugs and they are all 12V.
     
  9. joshkbomb

    joshkbomb 1/2 ton status

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    Okay, I tested my voltmeter on some batteries and it looks like for every 6V it reads 1V high. This would account for the weird readings. I guess that's what I get for buying a $15 multimeter.
    Although I still don't know about the overheating of the tach. Could it be bad? Can I get it fixed?
     
  10. BlazerGuy

    BlazerGuy 3/4 ton status

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    [ QUOTE ]
    Thanks for the info. The links still don't work, but I'll keep trying. I tested all the plugs and they are all 12V.

    [/ QUOTE ]

    You have to copy and paste the link into your browser... /forums/images/graemlins/waytogo.gif...for some reason it won't work when you click on it.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    for some reason it won't work when you click on it.

    [/ QUOTE ]

    Free hosting perhaps? /forums/images/graemlins/smile.gif No clue really, but cutting and pasting will work.
     
  12. Mav2u

    Mav2u 1/2 ton status

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    Shoot us a picture of what it looks like installed. I'm curious to see how it fits and looks.

    Mav
     

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