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m4-atx ignition cable problem

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  • m4-atx ignition cable problem

    I have a m4-atx on my carpc.. and also have an ON - OFF - ON Switch on the ignition cable

    on - power from the ignition so it turns on and off with the car...
    off - no power carpc stays off all the time
    on - power from an always on source

    if I turn on the car the comp boots fine if I turn off the car the PC shuts down how it should be. but if I move the switch to any position while the pc its on the computer shuts down as if I had taken the power cable off from the power supply. I changed the switch tested the voltage on the cable to see if it was getting a spike on voltage making the m4 to shut down but everything was good

    I have the cable that gets the 12v from the ignition on the fuse block.. which works good with the key, but if I disconnect that cable manually it also shuts down the PS/pc.

    any ideas?

  • #2
    Are you sure the cable from the fuse block is going to the ACC/IGN line on the M4?
    It sounds like you have it running to the constant 12v line, so when the ignition is cut off, it's cutting power to the PSU (and subsequently the PC).
    Have you looked in the FAQ yet?
    How about the Wiki?

    Under normal circumstances, a signature would go here.


    • #3
      yeap, already check that. the ignition cable its the one in the middle and its a 14ga cable. the one with constant power its a 10ga and that one comes from a power block which runs directly from the battery

      I want to check the ground cable maybe moving it to another area to see if i get better ground. it might not have a good ground but dont know if that could be causing my problem..

      I have another m4 I want to swap them to ruled out the PS but i dont have much time now with the holidays...


      • #4
        I just disconected the ignition cable directly at the ps and it worked fine

        im going to make a sketch of the wiring to see if anyone finds anything wrong with it.. (if a remember how its everything connected its been a long time.. and now its that I want to fix that) it did work b4 at one point..


        • #5

          thats the diagram... nothing special and it was working before