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  • Need help w/ a resistor

    Ok, I'm wiring a .5W 1K resistor in. It has two sides.


    right now the wire is like this:

    ==================


    and the resistor is this:

    ---[|||]---

    so do i wire it in like this?

    ======---[|||]---======

    Does it matter which direction I wire it in? (like is there an input and an output)

    Or am i completely wrong and do i wire one side into the wire with the resistor and wire the other side to ground, effectively T-ing into it?

  • #2
    what are you trying to do with it?
    this could affect how you wire it.
    Yeah, well I'm gonna build my own lunar space lander! With blackjack aaaaannd Hookers! Actually, forget the space lander, and the blackjack. Ahhhh forget the whole thing!

    Comment


    • #3
      I'm not quite sure, really.

      I'm just told I have to wire in this 1k resistor into my piggyback for it to be able to read the signal.

      Or do i do it like this?

      ECU wire #88:

      MAF------------------Piggyback
      .................|
      ............... [ ] <--resistor
      .................|
      .................|
      .................- <--Ground

      Comment


      • #4
        still a tough call.
        in the first instance you might require the resistor to limit the current draw from the piggyback unit.
        in the second, if the piggyback unit has a relatively high input impedance than the rsesitor may be required to impose a load on the MAF for it to provide a proper reading.
        Is the MAF connected to the ECU in parrallel with the piggyback or is the ECU connected to the ouput of the piggyback unit?
        Yeah, well I'm gonna build my own lunar space lander! With blackjack aaaaannd Hookers! Actually, forget the space lander, and the blackjack. Ahhhh forget the whole thing!

        Comment


        • #5
          Originally posted by gt40
          still a tough call.
          in the first instance you might require the resistor to limit the current draw from the piggyback unit.


          in layman's terms?

          in the second, if the piggyback unit has a relatively high input impedance than the rsesitor may be required to impose a load on the MAF for it to provide a proper reading.
          Wait...so the resistor would affect the MAF or would it effect what the piggyback saw from the MAF?

          Is the MAF connected to the ECU in parrallel with the piggyback or is the ECU connected to the ouput of the piggyback unit?
          The ECU is an output from the piggyback.

          sensors-->piggyback-->ECU

          Comment


          • #6
            I'm guessing that the MAF output needs to see a load.
            the piggy back unit may not impose a load (ie it looks like an open wire to the MAF), so the reisitor should be wired from the MAF to ground to provide said load.
            Normally the ECU would provide this load, but since it is not directly connected to the MAF, the resistor is required.

            I'm just guessing on this, you should really talk to the company that makes the piggy back unit.

            you could do this:



            MAF======---------------[ ||| ]----------=======piggyback
            ..................|
            ..................|
            .................|-|
            .................|-|
            ..................|
            ..................|
            ...............GND

            and you would cover both options.


            btw there is no polarity on a resistor, you can't wire it backwards.




            edit to make connection more clear for monospaced fonts - thanks Spadnos.
            Last edited by gt40; 21 June 2004, 05:29.
            Yeah, well I'm gonna build my own lunar space lander! With blackjack aaaaannd Hookers! Actually, forget the space lander, and the blackjack. Ahhhh forget the whole thing!

            Comment


            • #7
              Hmm, that's a good idea. And it could only go one route...the easiest. Hmm.

              Comment


              • #8
                well, you'd be loading the MAF if you needed to, and you would also be limiting the current going to the piggyback, if that was the issue - you'd be covering all the bases, so to speak.
                FYI, the resistor to ground would only impose a load of 5ma at 5V, so it shouldn't harm the MAF in any way.
                Yeah, well I'm gonna build my own lunar space lander! With blackjack aaaaannd Hookers! Actually, forget the space lander, and the blackjack. Ahhhh forget the whole thing!

                Comment


                • #9
                  MAF? Piggyback?

                  AZ
                  There's an Opera in my macbook.

                  Comment


                  • #10
                    Car talk.

                    Comment


                    • #11
                      Mass Air Flow sensor, uses a heated wire to measure the amount of air going into the engine.

                      The piggyback they're talking about is a little gizmo that sits between the real drivetrain computer and some of it's sensors to change the engines performance.

                      Comment


                      • #12
                        Ah thanks

                        AZ
                        There's an Opera in my macbook.

                        Comment


                        • #13
                          Hmmm.

                          Do you know how much power the MAF takes?

                          Presumably, it's powered by a separate 12V line, and has an output to the ECU??? Or is it powered directly by the same line as the sensor outputs on?

                          The 'piggyback' is a separate unit that you want to monitor MAF output from, right? (sorry - my background is electronics, not cars).

                          If you use the two resistor option, you will be dividing the MAF output in half (if you use two identical resistors). That's a voltage divider circuit. (of course, that depends on where the power for the MAF comes from....

                          Well - don't listen to me, I have no idea what I'm talking about

                          - Steve

                          Comment


                          • #14
                            typically the maf has a signal return (GND) signal line (0-5V) which is dependant on actual airflow, a reference voltage line (5v) and a 12V power line.
                            And actually it would only be a voltage divider if he did this:



                            MAF signal====-----[ | | | ] ---------------====Piggy back
                            ................................................|
                            ................................................|
                            ...............................................|-|
                            ...............................................|-|
                            ................................................|
                            ................................................|
                            ..............................................GND

                            I think you are confusing the MAF line as being an Input, when in fact it is an output.
                            Basically the piggy back unit modifies the signal from the MAF going back into the ECU
                            Yeah, well I'm gonna build my own lunar space lander! With blackjack aaaaannd Hookers! Actually, forget the space lander, and the blackjack. Ahhhh forget the whole thing!

                            Comment


                            • #15
                              Re: Need help w/ a resistor

                              Originally posted by Kooldino
                              Does it matter which direction I wire it in? (like is there an input and an output)
                              Don't know exactly what you mean, but if you are talking about polarity of resisitor, there is none. (I think I am stating the obvious here )

                              Comment

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