Electrical 93 Lx 5.0 Timing Advance Issues Need Help Bad

Discussion in 'Fox 5.0 Mustang Tech' started by missin'5.0, Aug 30, 2013.


  1. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Connect a 560 ohm 1/2 watt resistor on the white/pink wire that has the 2.7 volts on it. Connect the other end of the resistor to a good ground. Then go through the voltage measurements again.

    See Radio Shack for the resistor.
    Radio Shack 560 ohm 1/2 watt resistor, 5 pack, Model: 271-1116 | Catalog #: 271-1116
    $1.49
     
    #21
  2. missin'5.0

    missin'5.0 New Member

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    I can try that, I think im understanding correctly. Can you maybe kinda pain the picture ? One side of resistor to circuit wire then other side to ground?
     
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  3. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Yes.
    If there is some small leakage, the 560 ohm resistor will pull that to ground. The resistance is large enough that you won't draw enough current to damage anything, but still pull down any stray leakage voltage to 0 or a very low value.

    If that does the trick, then we need to go looking for the source of that voltage leak...
     
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  4. missin'5.0

    missin'5.0 New Member

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    Ok cool good idea man, that circuit only gets 12v key in start all the way forward position. .. that resistor going to ground wont ground and short that 12v in start will it?
     
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  5. missin'5.0

    missin'5.0 New Member

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    Ok just verified 4.5 volts coming right out of pin 30 on pcm. I clipped 5 inches from plug I put a new pcm in a week or so ago and that did nothing . Im on my way to radio shack now to pick up the resistor.
     
    #25
  6. missin'5.0

    missin'5.0 New Member

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    The resistor to ground got it down to 1.5v, car still will not advance timing until its completely grounded to 0volts. If I bypass the resistor and go straight to ground it will operate correctly, however at that point car wont restart since the start wire is completely grounded
     
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  7. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Then you have a leak from another circuit that is connected to the same wire or some undiagnosed problems in the TFI module circuit. It's time to start looking at what is sharing the wire.
     
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