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Wiring Diagram - Will This Work?

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  • Wiring Diagram - Will This Work?

    I've been going over this 6 million times in my head, and it's now time to get a second opinion on it. However, a little background info first!

    my beemer has a timer on the main circuit, that shuts down after 15mins or so of no activity. this is to save the battery going flat when lights inside are left on etc. the circuit wakes up when the keyfob is pressed, or the door opened (usualy by keyfob).

    what I'd like to acheive is this:

    for the carpc to go on when I press the keyfob
    for the carpc to go off when I switch off the ignition
    for everything to be completly off and isolated when the car goes to sleep
    ... unless I have the manual override, in which case all the above is ignored

    so to do this, I've come up with the following circuit diagram:



    1. when the car wakes up, the voltage from the CarAwake line, will go past D1, and down to RLY2 to enable the 12v supply.

    2. RLY1 is in the off position, and therefore the CarAwake voltage will pass straight through it, and down to M2A's IGN terminal.

    3. M2A will switch on M2B after a few seconds

    4. If the Ignition is NOT switched on, then after 15mins or so, the CarAwake current will be gone and everything will shutdown suddenly (I don't require graceful shutdowns as I use EWF).

    5. If the Ignition is switched on, the current will pass through D3 and make sure that M2A has power at its IGN terminal.

    6. Then the current will pass through D2, and put RLY1 in the on position. Now, CarAwake current passes through RLY1 and powers itself. This cuts off the CarAwake power to the M2's IGN terminal, and makes the Ignition power the only power source to it.

    7. When Ignition is switched off, the M2 will respond accordingly and shut down.

    8. After some time, the car will go to sleep and everything will be cut off for sure.

    9. If I want to stay in the car and work on stuff for a bit, I can trip SWT1 and ensure that this entire logic spaghetti is bypassed.


    My questions are:

    Does this look like it will work?

    Are there any concerns?

    What kind of diodes do I use for D1 D2 and D3?

    Have I gone diode mad?

    What kind of fuse values do I use for F1 and F2?


    I've just realised SWT1 doesn't need to be double throw, but hey, it's 3AM!!
    Current:
    [BMW E46 ///M3 Convertible]

    Previous:
    [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

  • #2
    as far as the on and off on the relay, im gonna need the names like 87a, 87, 30 so we can tell which is normally closed and normally open.

    it looks like your ignition is looping, but with the relay info it will be easier to tell

    Comment


    • #3
      hello. thanks for the reply. I didn't know about the a annotation meaning it's normally connected, until i just did some research now.

      I've modified the image to represent this correct notation.

      the looping is intented, so that once the ignition comes on, the CarAwake supply latches itself off and remains off. I'm questioning however if I've done this correctly.
      Current:
      [BMW E46 ///M3 Convertible]

      Previous:
      [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

      Comment


      • #4
        first off have u checked the polarity of your awake trigger and u might was to let the awake trip a relay, that would be the more cautious approch.

        otherwise it looks right

        ill look at it tomorrow when im fully awake. lol

        Comment


        • #5
          not sure about the polality, but I'll check. I'm pretty sure it's +ve.

          so are you suggesting to ditch D1, and replace it with a relay?
          Current:
          [BMW E46 ///M3 Convertible]

          Previous:
          [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

          Comment


          • #6
            add the relay to the existing circuit.

            it might be positive but if it is, most of the time they are really low amprage, on most cars they are activated by the dome light which is low amperage, if that is the case then u would have to it to trip the coil on the relay.

            what kind of car is it?

            Comment


            • #7
              it's a BMW 535i, 98. I'll probably branch off the power line that feeds the internal cabin lights. I've read of others connecting this directly to the m2-ign.
              Current:
              [BMW E46 ///M3 Convertible]

              Previous:
              [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

              Comment


              • #8
                I'd use 1N4004 diodes available at RadShck

                Common automotive relays draw .1 to .3 amps so a .5 amp fuse will do ya,.

                Does your car awake signal need to be latched by relay 1 ?
                Won't you loose it momentarily when the car is switched off ?
                could you not...

                Remove Relay 1
                Connect D1 Cathode to IGN
                Connect D2 Cathode to IGN
                Connect Sw1 ( + diode ) to IGN

                The diodes will protect the sources from reverse current flow.

                Comment


                • #9
                  Originally posted by billmee View Post
                  I'd use 1N4004 diodes available at RadShck

                  Common automotive relays draw .1 to .3 amps so a .5 amp fuse will do ya,.

                  Does your car awake signal need to be latched by relay 1 ?
                  Won't you loose it momentarily when the car is switched off ?
                  could you not...

                  Remove Relay 1
                  Connect D1 Cathode to IGN
                  Connect D2 Cathode to IGN
                  Connect Sw1 ( + diode ) to IGN

                  The diodes will protect the sources from reverse current flow.
                  1N4004 diodes it is! I've been waiting for that response! cheers.

                  as for the car awake signal being latched, I need it to be out of the picture when the key is switched on. so that I turn on the carpc via the keyfob, and it turns off via the ignition.

                  why do you think I will oose some power momentarily when the car is switched off? (answering a question with a question )

                  do you mean connect like this:

                  carAwake --->|-----+ IGN (M2)

                  CarIGN ------>|-----+ IGN (M2)

                  SW1 -------->|-----+ IGN (M2)


                  if so, this would mean when the car ignition goes on and then off, the carAwake like will continue to power the IGN of the M2, and therefore when I turn the car off, the M2 will stay on.
                  Current:
                  [BMW E46 ///M3 Convertible]

                  Previous:
                  [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

                  Comment


                  • #10
                    Originally posted by sama View Post
                    if so, this would mean when the car ignition goes on and then off, the carAwake like will continue to power the IGN of the M2, and therefore when I turn the car off, the M2 will stay on.
                    if the carAwake signal is from the interior light, then it normally should be off isn't it?

                    Comment


                    • #11
                      nope, it's the line that provides power to the light, prior to the switch connecting the bulb. this line goes off after 15mins of no activity in bmw's
                      Current:
                      [BMW E46 ///M3 Convertible]

                      Previous:
                      [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

                      Comment


                      • #12
                        Originally posted by sama View Post
                        1N4004 diodes it is! I've been waiting for that response! cheers.

                        as for the car awake signal being latched, I need it to be out of the picture when the key is switched on. so that I turn on the carpc via the keyfob, and it turns off via the ignition.

                        why do you think I will oose some power momentarily when the car is switched off? (answering a question with a question )

                        do you mean connect like this:

                        carAwake --->|-----+ IGN (M2)

                        CarIGN ------>|-----+ IGN (M2)

                        SW1 -------->|-----+ IGN (M2)


                        if so, this would mean when the car ignition goes on and then off, the carAwake like will continue to power the IGN of the M2, and therefore when I turn the car off, the M2 will stay on.
                        Sorry I re-read your post and realise you are using the car awake to maintain the IGN signal until car awake shuts off.
                        If that is the case disregard my suggestion.

                        Comment


                        • #13
                          that picture must be fresh

                          thanks for helping out
                          Current:
                          [BMW E46 ///M3 Convertible]

                          Previous:
                          [BMW E31 850CSi]|[BMW E39 535i]|[BMW HVAC Research]|[IBUS Scrolling Text]|[BMPuter]|[Velocity]|[TomTom]|[Vision]|[Space Navigator Driver]|[Super Fast Boot]

                          Comment

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