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Thread: Tachometer trouble

  1. #1

    Tachometer trouble

    just wondering if anyone else has had trouble running a video techometer
    off of the tach out put from an 0411 ECM im running a 02 escalade
    Programe and the tach is not working I have a good power and ground
    And a good connection at ecm I tryed a 680 ohm resistore for a pull up no luck
    Any ides would be great thanks

  2. #2
    Advanced Tuner Montecarlodrag's Avatar
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    Which tach are you using?
    Did you set up the tach output correctly?

    I have used as low as 480 ohm resistors to pull-up. Some PCMs don't work with 1K ohm for unknown reasons.
    Be aware that using low resistor values put more stress to the sink circuit of the PCM, it may damage the tach output.

    I have done it to a few swaps and they are working ok for more than 2 years, but use low resistor values only as a last resort.
    If you don't want to risk your PCM, use a converter like this:
    http://www.summitracing.com/parts/dak-sgi-8

    I'm searching for a cheaper alternative, no luck so far
    9 sec Montecarlo SS

  3. #3
    Quote Originally Posted by Montecarlodrag View Post
    Which tach are you using?
    Did you set up the tach output correctly?

    I have used as low as 480 ohm resistors to pull-up. Some PCMs don't work with 1K ohm for unknown reasons.
    Be aware that using low resistor values put more stress to the sink circuit of the PCM, it may damage the tach output.

    I have done it to a few swaps and they are working ok for more than 2 years, but use low resistor values only as a last resort.
    If you don't want to risk your PCM, use a converter like this:
    http://www.summitracing.com/parts/dak-sgi-8

    I'm searching for a cheaper alternative, no luck so far
    thank you for the input I am using a VDO tach that red line gauges installed in a factory 2000 Jeep Wrangler gauge cluster for me I am going to try a 1/2 watt
    680 watt tomorow and go from there. I have the dakota box at my shop if all
    Fails I will try that. Thanks again ill let you know what happens

  4. #4
    How do you know what ohm resistor to use. My GMPP harness manual says to use 5000 ohm, I have read online 1000 ohm, what gives? I have tried 5000 ohm & get nothing.
    Thanks,
    Scot