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  • Tiptronic (semi-automatic) gearbox

    Starting a new thread following on from Apache's one here, to detail what I've managed to do so far to create full manual control of the auto gearbox in a 1993 KZN130. If you're going to attempt this, I'd recommend reading that whole thread to get more of an idea of what's going on. I'd really appreciate any feedback or comments, as I'm neither an expert at electronics or Surfs... (managed to melt 2 chips and blow 1 fuse while getting this far...)

    I've just been for a test drive and have a fully working manually controllable auto gearbox. It's still sitting out in a messy breadboard, but working well.

    ECU pinouts are available courtesy of Apache and MattF in this thread. I've tapped into "+B" (pin number A12) for power when the ignition is 'ON', used one of the screws mounting the ECU as earth, and cut and re-directed S1 (C2), S2 (C15) and SL (C1) through my new hackery. These are the three solenoids in the gearbox. S1 and S2 control the gear selection, SL engages lockup (the drop in engine speed at approx 55mph). Lockup removes the torque converter from the loop, potentially increasing efficiency by 5-10% (similar to a manual).

    The gear signals are, with 1 meaning on (12V) and 0 off (earth):
    S1/S2/Gear
    1 / 0 / 1
    1 / 1 / 2
    0 / 1 / 3
    0 / 0 / 4 (OD)

    Here are the steps I've taken so far.

    First, remove the ECU cover in the passenger's footwell:


    Then make 100% sure you're working with the correct ECU signals by linking them up to LEDs and driving around watching them for a while:


    A hard on-off switch to change between the ECU lockup signal and a plain 12V signal shows that over-riding lockup is feasible and works in all gears:


    Next was to design a small circuit to give more sensible, safe control of lockup, only allowing it in 3rd and 4th gear. Thanks to Apache, on page 2 of the thread linked above, for the circuit diagram that got this whole thing going. The button hanging off the bottom right is an LED-lit push-to-make, which lights up when lockup override mode is active. The red LED on the board lights when lockup isn't allowed (1st or 2nd gear), the green LED lights when lockup is actually selected, including when simply doing over 55mph:


    This was then modified to include a 7 segment display to show the current gear, using the decimal point to mean that the gearbox is in lockup. The green and red LEDs were then removed:


    This is the stereo control paddle from behind the steering wheel on an old Laguna, which I'm using for controlling the gear changes:


    Finally, with the addition of some more logic chips and many, many hours of cutting jumper leads, here's a picture of the current breadboard circuit in the Surf. Note the mechanical 'on/off' switch to change between auto and manual mode, and the red led-lit push button for entering lockup on mode (works in manual or auto). The top strip of breadboard is unchanged from the simple lockup over-ride system:


    Annotated:


    A brief description of the system logic as it stands. A counting chip (CMOS 4069) is used to keep track of the current gear. I'm using offset binary, so it starts at 1 not zero: output 00 means first, 01=second, 10=third and 11=4. If for any reason it reaches number 4 or above (shouldn't ever happen), it instantly resets, and synchs to the auto box.

    The chip can be preset to a set number by feeding it the correct inputs and putting the 'preset' pin to 12V. This is done continually when the main switch is set to 'OFF' (auto mode), meaning the counter follows the auto box. A relay connects the S1 and S2 inputs and outputs, so all the circuit is doing is following (and displaying) the current gear.

    When the switch is moved to 'ON' (manual), the preset pin is grounded, so you stay in whatever gear it was in (can do this at any speed). The output of the counter is then translated to S1 and S2 signals, which are passed to relays to pass 12V to the output signals appropriately.

    Counting above 4 or below 1 is blocked, as is counting up and down simultaneously. Most of the logic chips are working to translate between pure binary counting (the 7 segment display), offset binary counting (the counter chip) and S1/S2 modes.

    One awkward thing about the counter chip is instead of having a 'count up' and a 'count down' pin, it has an 'up/down' pin and a 'count' pin. So if 'up/down' is high, it counts up, and vice versa. So if the pin is constantly pulled down, then to count up it must be pulled up before the count signal is sent.

    Also, the circuit must be protected against all the solenoids and relays by diodes. All 3 solenoid outputs must be protected.

    I'll draw up a full logic flow diagram and circuit diagram and post them here too when I have time.
    Andy
    http://www.surfingafrica.net

  • #2
    What an excellent writeup by both you and apache, been semi following apache's thread but not being anywhere near as knowlageable in these matters it did'nt take long to get "lost" i'll need to read several times to get the idea, well done both of ya
    Too young to die and too old to give a toss

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    • #3
      Excellent job Andy! Looks like you've saved me some work!

      Post the full diagram when you've got time - no sense in reinventing the wheel.

      Have you done a full range of tests, to see what happens if you do try to do things in non-standard order? In other words, now you need to TRY to break it in ways that could feasibly happen in normal or ham-fisted use. I'd start with stuff like :-

      What happens if the circuit loses power when you're driving, in the manual gears or in lockup?

      What happens if you hold the gearchange buttons down rather than just single presses?

      Does anything odd happen when you do stuff like key the transmitter on your CB? Switch on the wipers? Flick the lights to full beam etc (EMC is what I do for a living these days )

      A good idea for the proper version would be an overall screened multicore cable from your new circuit to the ECU, and put the new circuit into an earthed metal box - I have some proper RF-tight boxes if you need one. There should be plenty of filtering on the 12v line into the unit too.

      There'll be more than this, but you know where I'm coming from. In other words, what you've done needs to fail safe.
      Cutting steps in the roof of the world

      Comment


      • #4
        Andy, I'll be at the meetup at Mitsy's later this month. Flying over for it, but I'll bring whatever I've got done by that stage with me - could play with it for a bit there. Hopefully I'll have a decent working prototype together on stripboard by then, which I want to use for a while before getting a PCB made, just to check it's doing all I want.

        Had thought of shielding, double switching etc. Had to make sure you can't try and change up and down at the same time or it could count out of range.

        Couple of features - I've hooked the counter's output '4' and '8' pins to the preset pin so if it gets out of range, it will reset and synchronise to the auto box. Have also set it up to synch to the auto for the first 2 or 3 seconds when it gets power, so you always start in 1st.

        The breadboard is working, but I'm mostly completed drawing up a circuit diagram in Eagle which is slightly improved. Will use that to make the strip-board prototype.

        One thing, the 'OD OFF' light blinks slowly (on for about 0.5 seconds, off for about 5) whenever I turn on the manual override circuit - any idea what that means? Stops blinking as soon as I switch back to auto.
        Andy
        http://www.surfingafrica.net

        Comment


        • #5
          Originally posted by adpsimpson View Post
          One thing, the 'OD OFF' light blinks slowly (on for about 0.5 seconds, off for about 5) whenever I turn on the manual override circuit - any idea what that means? Stops blinking as soon as I switch back to auto.
          Probably a fault code. Might have to spoof the ECU.
          Cutting steps in the roof of the world

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          • #6
            Bring on the flappy paddles!!!!



            Good work mate.

            Comment


            • #7
              Originally posted by Apache View Post
              Probably a fault code. Might have to spoof the ECU.
              Yup, sounds about right. Will see what I can do as flashing warning lights spoil the look!

              Originally posted by RodLeach View Post
              Bring on the flappy paddles!!!!


              Good work mate.
              Thanks! And flappy paddles - do they have a strong following round here?? I never really liked them that much, but they do the job...
              Andy
              http://www.surfingafrica.net

              Comment


              • #8
                I'd be inclined to have a small joystick of some sort, with a forward and backward position only for up and down changes, fit somewhere near the gear selectors - or perhaps buttons on the steering wheel if its possible to use the slipring arrangement off a truck with cruise control?
                Cutting steps in the roof of the world

                Comment


                • #9
                  Originally posted by adpsimpson View Post
                  Thanks! And flappy paddles - do they have a strong following round here?? I never really liked them that much, but they do the job...
                  No idea ... Its just be not having enough money for a Lambo!

                  Comment


                  • #10
                    Pffff... I could do that I just don't wanna.









                    Comment


                    • #11
                      Matt pointed me to a thread on the Austrian forum where they were discussing similar things - here. He asked if I'd mind posting an update there, so thought I'd post the same thing here.

                      The simple lockup switch is a very easy hack (see the third picture in the original post), and will get a satisfying result for very little work. I was attempting full manual over ride of the auto box.

                      The way I was approaching it was to use lots of logic chips (AND, OR, NOR, NOT gates etc), which can operate at up to 15V. That's nice and easy, and has no programming, but means I was using 10 separate chips, with an unnecessarily large and complicated board. It'd be much easier to use a programmable micro controller, with a very simple programme.

                      PICs (programmable integrated circuits - micro controllers) run off 5V, so you'd need a voltage regulator to run the circuit, you'd also need voltage regulators on each of the input signal lines (the ECU signals). You need those signals so that your 'manual' selection follows the auto selection when in auto mode, so that when you switch to manual mode you are in the same gear. Voltage regulators are pretty cheap, so the overall complexity and cost would reduce enormously.

                      The outputs need passed through a transistor to a relay, which could then handle the 12V directly.

                      The reason I took it out of the truck is that when you drive for a long period, a warning light sometimes comes on (the OD light, flashing at about once every 2 seconds). The ECU then outputs the signal for 4th gear until it senses that it is back in control - so it's impossible to drop back into auto unless you're at high speed. It would really be necessary to understand what's causing the ECU to realise it's lost control, and spoof it to keep it happy. That may be much more work than the gear override...

                      The board I now have is working, and can be plugged in and out. It taught me a whole lot about how the box works, and if and when I get time I'll work on improving it to work off a PIC instead. But I wouldn't recommend attempting this unless you either have many, many hours to invest or already have a good understanding of how to use PICs.
                      Andy
                      http://www.surfingafrica.net

                      Comment


                      • #12
                        They're gonna love you calling them Austrian.

                        Btw, do you have a PIC programmer for working on the latest incarnation?

                        Comment


                        • #13
                          Originally posted by MattF View Post
                          They're gonna love you calling them Austrian.

                          Btw, do you have a PIC programmer for working on the latest incarnation?
                          Yeah so, about that auto spell checker...

                          I don't have a programmer, but I work in a uni so have access to one. I've got a nice little 4x20 alphanumeric display rigged up to a PIC with 6 temperature sensors, and still have a few spare inputs/outputs on the chip to display the current gear and perhaps control torque converter lockup.

                          Not far enough on to post pictures yet, and the surf is off the road just now with no coolant, so give it a few weeks and I'll get something posted up.
                          Andy
                          http://www.surfingafrica.net

                          Comment


                          • #14
                            Originally posted by adpsimpson View Post
                            Yeah so, about that auto spell checker...


                            I don't have a programmer, but I work in a uni so have access to one. I've got a nice little 4x20 alphanumeric display rigged up to a PIC with 6 temperature sensors, and still have a few spare inputs/outputs on the chip to display the current gear and perhaps control torque converter lockup.
                            Not 100% certain, but I think I may have one or two programmers knocking about in the workshop somewhere, if you fancy having a play with it at home too. Can't remember exactly which family of chips they're for, but if they may be useful to your testing?

                            Must admit, I'm intrigued in where this project might lead.

                            Comment


                            • #15
                              Originally posted by MattF View Post

                              Not 100% certain, but I think I may have one or two programmers knocking about in the workshop somewhere, if you fancy having a play with it at home too. Can't remember exactly which family of chips they're for, but if they may be useful to your testing?

                              Must admit, I'm intrigued in where this project might lead.
                              If one of them could handle a PIC, I'd certainly be interested... Can't remember offhand which series it was I was using, but I can check when I get home.

                              Slightly longer description of the problem that stumped me, to see if might recognise what's causing the problem.

                              When the manual override is engaged, the truck drives quite happily indefinitely until it attempts kick-down (ie changing down a gear at speed to get more power). At that point the ECU seems to realise it's lost control of the gearbox, the 'OD' light flashes at about once every 2 seconds, and the auto selection moves to, and stays at, 4th gear. It will still drive happily in the manual mode.

                              If at that stage I change it back to auto, it takes about 20 seconds to realise it has control again, during which time it stays in 4th gear. After that it's fine, but if I change to manual again it immediately knows it's lost control and goes into the fault mode again.

                              Turning off the vehicle completely seems to fully reset it back to square one.

                              So if anyone has any idea how to tackle what's happening, let me know!
                              Andy
                              http://www.surfingafrica.net

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