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Thread: Various Workings Of The LM, PM And The Sensors That Report To Them

  1. #1
    Garrett booster
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    Various Workings Of The LM, PM And The Sensors That Report To Them

    I am trying to familiarize myself with the workings of the LM, PM and the various sensors that feed information to them. I'm thinking that if I can understand these systems better, than maybe I could systematically go through and test or check each piece to try and find out why I am having the intermittent spark issue that I am having. Sort of a directional chart if you will. Check this, if it works then check this, if it doesn't work check this. I have been going through all of the connectors and plugs with no luck. Nothing changes. It can get expensive just throwing new parts at it with no clear direction to proceed from. Maybe someone can direct me to where I can find this info.
    Thanks

    - - - Updated - - -

    Oh, I almost forgot. It's a 1986 New Yorker T1.

  2. #2
    Hybrid booster Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: Various Workings Of The LM, PM And The Sensors That Report To Them

    I have the complete 1986 FSM set, I believe there is a flow chart for troubleshooting. To start out, I will tell you where one I was helping with a similar issue needed to look. There is a yellow wire from the LM to the PM that is called "anti dwell" it runs from pin 6 in the red LM plug to pin 10 of the 12 way on the PM and tells the PM to open the circuit. The yellow wire when grounded with power to the system (ASD control K19, DB/YL grounded) will open the negative side of the coil as a set of breaker points would firing the coil. I have an old HEI spark test plug with a 1/4" gap, you should be able to get a nice fat spark across that distance, if not, then your coil is probably on it's way out.

  3. #3
    Supporting Member Turbo Mopar Contributor
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    Re: Various Workings Of The LM, PM And The Sensors That Report To Them

    Hello,
    Here is a document that I found very helpful. It does require a working knowledge of electronics.
    https://drive.google.com/open?id=1KU...G4sth06cgfAzBA
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  4. #4
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: Various Workings Of The LM, PM And The Sensors That Report To Them


  5. #5
    Garrett booster
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    Re: Various Workings Of The LM, PM And The Sensors That Report To Them

    This is great info guys. Sounds like a pretty simple system if you know where to start looking.

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