Golf mk7: Auto Start/Stop disable switch - who wants to help?

[mattaus]

OK, so needing to kill time before I headed off to the gym I did go and have a fiddle (stop sniggering in the back).

I'll take better photos (during the day would be a good start) when I do an actual full install guide.

The good news! The pins are marked (forgive the ****ty camera):



And low-and-behold there is a yellow and black wire connected to socket 10. I was unable to test the voltage on this because I did not have a lead for my DMM small enough to fit anything. I'll have to raid my electronics box for something that will work.

Now the switch cluster itself looks like this:



I'm hoping Don's plan involves wiring into the plug that goes into the bottom of the 3 switch cluster rather than the actual S/S switch itself, because bugger me if I could get the cluster apart. I'm sure it's possible but this stuff is fragile and I do not want to snap something 10 day old car just yet!

My thoughts are that there will be no need to pull the switch assembly apart because one of those 10 sockets on the wire harness will surely be responsible for sending the ground signal back to the brains? It's likely obvious from the diagram's Don has already included but I'm in a hurry and just wanted to get this up before I had to leave for a few hours. Hopefully the brains trust will have answers for me when I come back

Sorry if this doesn't really tell us anything helpful!

- Matt

[DV52]

OK, so needing to kill time before I headed off to the gym I did go and have a fiddle (stop sniggering in the back).

I'll take better photos (during the day would be a good start) when I do an actual full install guide.

The good news! The pins are marked (forgive the ****ty camera):



And low-and-behold there is a yellow and black wire connected to socket 10. I was unable to test the voltage on this because I did not have a lead for my DMM small enough to fit anything. I'll have to raid my electronics box for something that will work.

Now the switch cluster itself looks like this:



I'm hoping Don's plan involves wiring into the plug that goes into the bottom of the 3 switch cluster rather than the actual S/S switch itself, because bugger me if I could get the cluster apart. I'm sure it's possible but this stuff is fragile and I do not want to snap something 10 day old car just yet!

My thoughts are that there will be no need to pull the switch assembly apart because one of those 10 sockets on the wire harness will surely be responsible for sending the ground signal back to the brains? It's likely obvious from the diagram's Don has already included but I'm in a hurry and just wanted to get this up before I had to leave for a few hours. Hopefully the brains trust will have answers for me when I come back

Sorry if this doesn't really tell us anything helpful!

- Matt

Matt: Clearly I have chosen the correct co-inventor. As a well known Jedi gnome once said "strong with this one - the enthusiasm is"!

On a more serious note. Just get hold a couple of sewing needles and shove them into the connector space, attach the multi-meter leads to the bits that stick-out! I agree with your method of approach - better to connect to the back of the switch module.

If you look at my post#1, you will see that the signal wire to pin #4 is black/blue. You should see this colour wire in the rear of the connector loom (on the opposite side to the Black/Yellow wire.

If I could be so bold as to suggest a simple test before you connect the S/S kill switch to the Black Blue wire . Using those sewing needles that I mentioned earlier, pierce the Black/Blue wire with the sewing needle so that the tip goes through the copper wire. Then hook-up the multimeter leads to the needle-end and the other lead to an earth point. With the multimeter on DC volts, then press the VW S/S button and check that you have a short to earth. If you get this short every time that you press the S/S button, you have the correct wire. Incidentally, I have no idea what voltage the multi-meter will read with the S/S switch not depressed - please tell me
Cheers
Don

[pipedwho]

If you want a simpler install, consider using the pull up resistor on the button into a diode (and series resistance if necessary) to charge up a reservoir cap for the microcontroller supply. The micro and a drive FET should take very little power and the cap should still have sufficient charge to free wheel while the pull-up is being shorted closed.

[mattaus]

Matt: Clearly I have chosen the correct co-inventor. As a well known Jedi gnome once said "strong with this one - the enthusiasm is"!

On a more serious note. Just get hold a couple of sewing needles and shove them into the connector space, attach the multi-meter leads to the bits that stick-out! I agree with your method of approach - better to connect to the back of the switch module.

If you look at my post#1, you will see that the signal wire to pin #4 is black/blue. You should see this colour wire in the rear of the connector loom (on the opposite side to the Black/Yellow wire.

If I could be so bold as to suggest a simple test before you connect the S/S kill switch to the Black Blue wire . Using those sewing needles that I mentioned earlier, pierce the Black/Blue wire with the sewing needle so that the tip goes through the copper wire. Then hook-up the multimeter leads to the needle-end and the other lead to an earth point. With the multimeter on DC volts, then press the VW S/S button and check that you have a short to earth. If you get this short every time that you press the S/S button, you have the correct wire. Incidentally, I have no idea what voltage the multi-meter will read with the S/S switch not depressed - please tell me
Cheers
Don

Co-inventor? Mate, I'm the guinea pig!!!

Fortuitously one of my failed attempts to photograph the plug numbers shows the black and blue cable of wonder:



So my plan of attack once I have the parts will be to:

1. Needle in the BY wire and and a needle in the GND wire (pin 1) to test the voltage supplied by the BY wire.
2. Another needle in the BB wire along with the one already in the GND wire to test for a short to earth. I will hopefully remember to report back the resting voltage.
3. Attach the S/S device to the 3 needles and see if it works when I start the car.

The switch cluster will be plugged in the entire time. It may be tricky because there is almost no slack on the wire loom, but I'll try my best.

If you want a simpler install, consider using the pull up resistor on the button into a diode (and series resistance if necessary) to charge up a reservoir cap for the microcontroller supply. The micro and a drive FET should take very little power and the cap should still have sufficient charge to free wheel while the pull-up is being shorted closed.

Is this in reference to Don's design, or AJW's? Or am I missing the mark entirely lol?

[DV52]

Matt: I think what pipedwho is suggesting is to create a parasitic (low) power drain into a low loss capacitor from the signal on BCM PIN#60. The capacitor acts as an energy storage device and it becomes a power supply to run both a microprocessor and the FET switch that I posted earlier.

The micro would be programmed to produce the correct timing pulse to short PIN#4 on the switch module. Because the establishment of the parasitic power supply is self regulating for the Auto S/S kill switch, there would be no need for the 5 sec time delay in my design (and the delay in AJW's circuit). The duration of the actual S/S kill pulse would need to be carefully chosen bearing in mind the limited energy in the capacitor (unfortunately the S/S kill signal would also short-out the parasitic power supply - with the diode free wheeling as pipedwho says). Plus there would only need to be two wires in the Auto Kill switch.

What a truely inspired and sublimely elegant suggestion! Pipedwho's idea places the Auto S/S kill switch more intimately into the electrical operation of BCM signal. But the crucial bit in pipedwho's suggestion is (I think) that success of the circuit depends on being able to fool the BCM into believing that the parasitic current drain isn't happening.

Problem is that I just don't know anything about the electrical characteristics of the signal from BCM PIN#60. This is the same problem that exists with both my and AJW's design (sorry pipedwho - this isn't meant as a criticism, its just a statement of fact).

But, I think that pipedwho's suggestion is an intellectually superior and a much better engineered concept (than my clunky design). And it would be easier to install. It just needs more time and more R&D than I have available - but perhaps another forum member could pick-up this baton and run with it?

Fact is that there is no right solution to this problem - there are just different solutions

Don

[pipedwho]

Golf mk7: Auto Start/Stop disable switch - who wants to help?

Thanks dv52 for that description. You're right that someone needs to measure (or find from a schematic) the value of that pull up resistance to determine if it's of low enough value to be useful.

Also, it may be useful to 'steal' power from multiple buttons at the same time. This would both add more compliance at startup, and allow a smaller cap to be used as it's unlikely anyone will press more than one button at a time.

This is one or more extra wires, but they are all coming from approximately the same area making it easier to install without pulling the whole dash apart.

(Just putting this out there as once someone has done this the ease of installation will determine how many people will consider using it.)

[AJW]

Mattaus how hard was it to pull the centre console apart - tried to find a Video but haven't had much luck.
How much room is under the switch assembly?

Also good to know that there might be 12V in the loom close to the switch.
Looks like we should be able to fit it all under the switch.

I know my circuit is pretty conservative but it was designed without knowing exactly what the rest of the electronics is doing in the car.
I also feel better knowing that it has some isolation from the car using a relay in case something goes wrong - my PCB has about $15 in parts, I'm sure the module that it connects to costs more than that.
I even added a SMD fuse to the PCB just to be super careful.

The thing with whatever design gets used is it needs to work 100% of the time.
If under some combination of circumstances, like turning the car off and on quickly, it doesn't work it will be as bad as having to turn it off every time the car is started because you wont be able to trust it's behavior.

Looks like we've got a bit of a team going here so that should help sort it out.

[mattaus]

Any solution that does not rely on a uC is a better solution in my opinion. Code = bugs, although this would be so simple it'd be a challenge to leave any game breakers in the lines. I know I suggested it but my mouth (or fingers in this case) often works faster than my brain...

Regardless, I'm happy to go with the most robust solution and the one that is the easiest to install. As I mentioned earlier the wiring loom does not have a lot of slack on it. 3 wires should be easy to tap into, any more and you're asking for trouble. I really think you can forget about nicking power from more than one switch because this would require disassembly of the switch cluster. The problem with that is it looks to be very difficult, and even if you get it apart it seems like quite a dense object so my assumption is that there won't be a lot of space inside. I can't even see where said wires would exit.

Mattaus how hard was it to pull the centre console apart - tried to find a Video but haven't had much luck.
How much room is under the switch assembly?

Like any new car it was hard but only because I was super nervous of breaking anything. I did take other photos that were intended for a "How To" but they need to be better. Regardless, later today I'll post a guide on how to get everything apart and just replace the pics with better ones later on.

There is a fair amount of room under the switch but it's a cavity that is not finger friendly. You could easily 'dangle' a module in there but if you drop it I'm not sure how easy it would be to get the module back out...

I know my circuit is pretty conservative but it was designed without knowing exactly what the rest of the electronics is doing in the car. I also feel better knowing that it has some isolation from the car using a relay in case something goes wrong - my PCB has about $15 in parts, I'm sure the module that it connects to costs more than that. I even added a SMD fuse to the PCB just to be super careful.

The thing with whatever design gets used is it needs to work 100% of the time. If under some combination of circumstances, like turning the car off and on quickly, it doesn't work it will be as bad as having to turn it off every time the car is started because you wont be able to trust it's behavior.

I like this mentality a lot.

[mattaus]

This will do for now. I'll do neater instructions up when I have the test device along with a video instruction if it looks any good.

What you start with and where the clips are all located:


Pulling the gear selector trim. Note you need to pull towards the dash and up as there are tabs on the bottom. Do not pull up and towards the boot.


Just showing you the clips that are holding the trim in pace:


How to remove the bottom trim which must be taken out to get to the tab holding the switch cluster in place. The tabs to the extreme left and right are easy to get out as there is a gap underneath you can easily slip a thing tool under to push the tabs to the doors of the car, and then pull the trim up. The two more central tabs at the bottom are much trickier because the only way you can get to them also tightens them up! I got them out by using the same tool I used on the outer tabs, and 'working' my way towards the tabs, twisty the tool to gently pull the trim upwards. Whatever it does, it works:


This just shows you where the wiring loom attaches and the tab that holds the switch cluster in place from a different angle:

[DV52]

Matt: Looking at this nice picture I notice that you don't have an TCS/ESP switch on your car. Just a suggestion, but instead of splicing the Terminal 15 wire to the Black/Yellow wire, can you insert a mating pin connector into the front of the switch where the TCS/ESP switch would have been?
Don

[mattaus]

Forgive my stupidity, but isn't the very bottom button on the left hand switch cluster the traction control switch? The one with the car and squiggly lines. Or is TCS/ESP different?

[DV52]

Forgive my stupidity, but isn't the very bottom button on the left hand switch cluster the traction control switch? The one with the car and a squiggly lines. Or is TCS/ESP different?

Matt: Of course that's the correct switch - I must be loosing-it (sorry). The first place that I go blind is in my eyes!!
Don

[mattaus]

lol, all good! I'm discovering new things on my car every day so I had no idea if you were right or not. At least what I thought was traction control is in fact exactly that

[DV52]

Interesting Timing , pardon the pun.
I've been working on this also while I've been waiting for my car to arrive - hopefully should have the car next week.
I have a prototype built using a NE556 and a PhotoMos relay (G3VM-61G1) + external timing bits.
Also similar timing, I think mine is delayed for about 10secs + 1sec relay on pulse.

Here's my current circuit:-



I'm planning to do it all with SMD components and this is the PCB layout - single sided.
It has the NE556, G3VM-61G1 solid state relay for isolation + smd fuse just in case.



This is a picture of how big the PCB will be when I get around to making it, it's about 45mm x 24mm x ~8mm

AJW: just had another look at your (excellent) design. It looks like a dual mono-shot configuration with the first timer output being capacitor coupled to trigger the second mono (albeit I'm a bit confused about the need for the 10k pull-up resistor from pin 5).

I am impressed at the extent to which you have conditioned the trigger signal to ensure reliable start-up (both for pin 6 and for the reset pin 10) - and I thought that I was being ultra-conservative LOL! You have adopted a wise approach given the lack of information and the early days in our understanding of the car's electrical environment for the S/S kill switch. It might be possible to refine both our designs in subsequent versions.

The PCB screen and track layout clearly contemplate the solid state FET relay and the current limiting resistor, where as your wiring diagram suggests an electromechanical device. Will you be able to overlay the coil-relay over the PCB tracks on your PCB design, or will you put-in a second set of pads?

Mattaus has promised to provide feedback on my device, but I'm very interested in hearing about your observations (as indeed will be others reading your posts). Please keep us informed

[mattaus]

I'll test whatever you guys dream up, and gladly pay for and permanently install whatever is deemed the best solution