Tach doesn't work

Discussion in 'High Tech Retrofits' started by badazz81z28, Sep 27, 2017.

  1. badazz81z28

    badazz81z28 Veteran Member

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    Using the LS7 GMPP harness, there is a tach output that the instructions state is a 2 pulse output. I set the tach to accept 2 pulse but nothing. I checked the wire continuity ands it's good. Checked for voltage, hard to check but something is there.

    How can I actually to see if the tach is working? All Worked fine before I pulled the LS1.
     
  2. badazz81z28

    badazz81z28 Veteran Member

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    Btw, it's an Autometer ultra lite
     
  3. Goat

    Goat Veteran Member Lifetime Gold Member

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    My instructions state that the signal is a low voltage square wave and some tachs may have a problem reading it. It talks about installing a 5k ohm/1/4 W resistor...
     
  4. badazz81z28

    badazz81z28 Veteran Member

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    Why LS1 worked fine , that odd
     
  5. badazz81z28

    badazz81z28 Veteran Member

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    Not much of a computer person...where do you buy resisters other then online?
     
  6. nobreaks254

    nobreaks254 Veteran Member

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    Radio shack
     
  7. CaliCamaro75

    CaliCamaro75 Veteran Member

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    If radio shack is not around anymore. You could try computer repairs shops
     
  8. reedld

    reedld Veteran Member

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    I read that there are less than 50 stores left nationwide...makes it tough for little things like this. I really liked my local radio shack.
    Amazon Prime is a suggestion, 2 day shipping is probably the fastest other than a PC repair shop.
    Good luck
     
  9. Goat

    Goat Veteran Member Lifetime Gold Member

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    From my instructions...
     

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  10. badazz81z28

    badazz81z28 Veteran Member

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    Another member have me different advice. Create a pin on J1 pin 24 and splice 24 with 25 (current tach out on J1). Worked!

    He told me pin 24 is already a pull up signal and he was right and no resister
     

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