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Tach adapter for 1999-2004 PCM without tach output

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    Tach adapter for 1999-2004 PCM without tach output

    Shematic:
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    It's much cheaper to build this if you have the skills than you buy a tach adapter that goes on the power wire to the coils. Use at your own risk. I'm not responsible for you screwing up your car hacking into the wiring.

    That said... now a video of this stuff in action via breadboard. Once everything is installed permanently, I'll post pics/vid of that too.


    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

    #2
    Conditioning portion of the circuit isn't needed. In fact, it failed on my car and prevented the tach from getting a signal. Now I have raw signal coming from the diode array. I also seem to have multispark capability so the tach will not read correctly at idle sometimes (jumps up around 2-3x of actual). I've confirmed this with an oscilloscope showing multiple pulses per cylinder. Not sure if that is misfire prevention or what, but it's there.
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    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

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