# Adding a Button on console for Front Camera



## jonnieb2018 (Nov 15, 2018)

I want to be able to add an additional button on the front console row of buttons.

Is this an easy job to do? I currently have 5 on there (see picture) but if its possible I want to add a 6th like the P button.

I will then need to work out the wiring to use this as a 'on off switch' for a front camera connected through Xcarlink which I am installing to add mobile mirroring and video inputs.

I think I might try and get hold of a replacement row of buttons and have a tinker... as I wan to make this look as OEM as possible without any cheap looking buttons in the car.


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## macaddict111 (Jun 13, 2018)

Hey man! That's a fantastic idea actually, that center bank of switches is one of my favorite pieces of switchgear. I've posted the relevant page of the wiring diagram for the park assist button (be careful, there's also a 7th rare button on the very right for _parallel parking_ assist that's not on the product you showed).

Not sure how familiar you are with wiring diagrams, but the bottom grey block EX22 is the center switch module. It connects to the outside with the T20b 20-pin connector on its back. E266 is the Park Assist button. The top "common" line in the EX22 block is supply (3.3V? 5? 12 V?). The bottom is ground (those are shown on another page). You can see that the E266 switch simply shorts the T20b connector pin 4 to ground when pressed. There is also the K136, the indicator light on the Park Assist switch. You'd like just leave this disconnected/unused.

You would have to somehow splice into the 20-pin connector and get a wire connected to pin 4 of the connector or the wire coming from that into the harness (if the wire is even provided, likely not) to use the park assist as a pull-down to ground switch. Obviously all at your own risk, but I hope it's a start. Let me know if I can help anymore!


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## jonnieb2018 (Nov 15, 2018)

macaddict111 said:


> Hey man! That's a fantastic idea actually, that center bank of switches is one of my favorite pieces of switchgear. I've posted the relevant page of the wiring diagram for the park assist button (be careful, there's also a 7th rare button on the very right for _parallel parking_ assist that's not on the product you showed).
> 
> Not sure how familiar you are with wiring diagrams, but the bottom grey block EX22 is the center switch module. It connects to the outside with the T20b 20-pin connector on its back. E266 is the Park Assist button. The top "common" line in the EX22 block is supply (3.3V? 5? 12 V?). The bottom is ground (those are shown on another page). You can see that the E266 switch simply shorts the T20b connector pin 4 to ground when pressed. There is also the K136, the indicator light on the Park Assist switch. You'd like just leave this disconnected/unused.
> 
> ...


Thats fantastic thankyou Mac!

I am familiar with wiring diagrams having done extensive mods on my A5 some years back -thats just what I need. I have managed to get hold of a full row of switches off ebay germany so can have a tinker on a test bench before installing to make sure it all works as it should.

So the switch is a ground connection so would it work if I have a live feed to the camera, the negative feed to this console parking switch so when I press the button it completes the negative circuit, switching on the camera? or maybe I can bypass all of this and get the switch to work independently with some adaption and connect the live up -this way there is no permanent live to the camera which there would be in the first option (change the connection inside the switch from bottom bar to the live bar (if the bar is 12v - I would need to check this)
There wont be a wire in there but I can get the appropriate pin and put it into the connector at pin 4 or Pin 3 if I use the park assist steering button,

So the switch I have got hold of is in the pic attached. It has two buttons on right which would be spare, one for this mod and I can use my current blanking switch from my existing console for the other one -blank it out as I wont need it.

So the E581 Parking assist steering button would be the far right switch. Having said that the park assit button would prob be more appropriate for this mod

















J


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## K4RL (Feb 23, 2018)

FYI - uk pre MY2017 cars have the switches the opposite way round with the drive select switch being the closest to the driver. Audi cost cutting from 2017 had all cars fitted with left hand drive set up, so drive select furthest from driver.

Karl


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## macaddict111 (Jun 13, 2018)

jonnieb2018 said:


> So the switch is a ground connection so would it work if I have a live feed to the camera, the negative feed to this console parking switch so when I press the button it completes the negative circuit, switching on the camera? or maybe I can bypass all of this and get the switch to work independently with some adaption and connect the live up -this way there is no permanent live to the camera which there would be in the first option (change the connection inside the switch from bottom bar to the live bar (if the bar is 12v - I would need to check this)
> There wont be a wire in there but I can get the appropriate pin and put it into the connector at pin 4 or Pin 3 if I use the park assist steering button,


Hey man. Noooooo definitely 100% can't use these switches to carry any current, they only provide a pulse to ground for a computer. I doubt these switches could carry more than 10 mA. 99% of the switchgear on modern, nice cars does nothing but provide a digital signal to a computer somewhere. This is a fantastic thing as it makes the switches extremely reliable, consistent (ever noticed how literally all the switches in the car feel exactly the same?), and small, so you can put lots together. It also means the actual electrically-stressful switching of the load (whether it's your window or defrost or headlights) is done with a FET which never wears out, or a bank of relays somewhere that can be replaced for $5 each. It also means trying to overstress any of the switchgear or more importantly, the lines that connect to the chasis computer for example, could lead to very expensive failures (I think the chasis controller in this car costs more than the ECM).

You should read up on pull-up resistors, but in the normal case, the controller that one of these switches connects to provides 3.3 or 5 V through a very large (thousands of ohms) resistor. When the switch isn't being pressed, there's no load on the line, and the circuit carries a positive voltage through the pull-up resistor to the computer which sees 3.3 or 5 V at an input pin. When you press the button, you complete a zero ohm path to ground. Since there is no resistance to ground vs a large one to +5 volts, the line goes to close 0 volts while the switch is pressed, and the computer detects this signal and runs some code.

All this to say, you certainly can't use the switch or the internal ground path inside the switch to carry any current, and I doubt you're going to have much luck taking apart the switch to modify it as it's likely all on a PCB. Plus, if you start modding the switch bank, you're also messing with the numerous computers those other switches could be connected to.

You'll need to use a relay module, or a controller for example that can provide a pull-up circuit for the line, and can receive a 0V switch-on signal without using any current. No simple way to modify or use existing switchgear on computerized cars sadly, but if you're connecting to something with a computer like a microcontroller board (if you're a nerd like me), they work perfectly.


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## jonnieb2018 (Nov 15, 2018)

K4RL said:


> FYI - uk pre MY2017 cars have the switches the opposite way round with the drive select switch being the closest to the driver. Audi cost cutting from 2017 had all cars fitted with left hand drive set up, so drive select furthest from driver.
> 
> Karl


I did wonder why some where on he left and ones on the right and if mine was wrongly put in for a RH drive model (drive select on left hand side)


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## jonnieb2018 (Nov 15, 2018)

macaddict111 said:


> jonnieb2018 said:
> 
> 
> > So the switch is a ground connection so would it work if I have a live feed to the camera, the negative feed to this console parking switch so when I press the button it completes the negative circuit, switching on the camera? or maybe I can bypass all of this and get the switch to work independently with some adaption and connect the live up -this way there is no permanent live to the camera which there would be in the first option (change the connection inside the switch from bottom bar to the live bar (if the bar is 12v - I would need to check this)
> ...


I see, but you have lost me now Mac at the end paragraph! I know about basic electrics but this is a step beyond me 

~Not sure what I do here now -the switches may be removable (but probably not as cant see any single ones on ebay) -If they are not removable then I may need to take apart the whole unit and identify the circuit from Pin 4 - see what's going on inside and how easy or how difficult this is going to be.

What would a wiring diagram be like with the relay module










We will see when it arrives.

Thanks again Mac.


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## ReTTro fit (Nov 9, 2014)

And some have red illumination and some are white

Sent from my iPhone using Tapatalk


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## Dino_Donis (Apr 19, 2004)

Another note loosely covered by previous posts is that I don't think the switches latch i.e. they only stay on (connected) for a long as you hold them down (momentary switch). So you would have to have some latching mechanism that is powered from a more permanent power source i.e. switch ignition. You need some sort of logic to turn ON and turn OFF your camera when the switch is operated...there is an electronic device called a D-type flip-flop which does this but then you need some sort of circuit board and a logic supply (5v/3.3v) to power the device....


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## jonnieb2018 (Nov 15, 2018)

Dino_Donis said:


> Another note loosely covered by previous posts is that I don't think the switches latch i.e. they only stay on (connected) for a long as you hold them down (momentary switch). So you would have to have some latching mechanism that is powered from a more permanent power source i.e. switch ignition. You need some sort of logic to turn ON and turn OFF your camera when the switch is operated...there is an electronic device called a D-type flip-flop which does this but then you need some sort of circuit board and a logic supply (5v/3.3v) to power the device....


You are quite right Dino and I have thought about this - this will be the next challenge. I was thinking do you remember the old courtesy light delay relay when you opened the car door for about 10-15 seconds. I wonder if there is a way of using a similar principle...but in a more modern approach??








A d type flip flop I would need to read up on as I know nothing about them other than what you wear to the beach.... 

I need a diagram drawing up for this I think - I just haven't got that depth of knowledge on circuitry unfortunately.

Thanks for this
J


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## phazer (Apr 2, 2018)

A simple latching relay will do what you want, the button press triggers a state change but the "other" side of the relay carries the power for the accessory, in this case the camera.


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## macaddict111 (Jun 13, 2018)

Again, even trying to energize a relay coil with a switch like this is too much. The only thing you can do with that switch bank is to use the line going from the switch as a signal to a microcontroller that doesn't pull any current on the line and also has an integrated pull-up resistor. Not to be rude but if that doesn't make sense, read up on why we use line pull-up's and how to safely connect one to the switch bank, otherwise you could start causing all kinds of electrical problems.

This switch isn't going to give you a "pulse" of positive voltage to drive a relay. It's going to take a line that has a normally very weak positive voltage and make it 0 when pressed. Some company out there has to make a relay or FET module that can supply the pull-up voltage and toggle a relay output based on a pull-down switch like this, but I wouldn't know where to start looking...


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## RobinHelsby (Mar 24, 2018)

jonnieb2018 said:


> I did wonder why some where on he left and ones on the right and if mine was wrongly put in for a RH drive model (drive select on left hand side)


Not just yours - mine is the same - Drive Select furthest from the driver (RHD)


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## phazer (Apr 2, 2018)

macaddict111 said:


> Again, even trying to energize a relay coil with a switch like this is too much. The only thing you can do with that switch bank is to use the line going from the switch as a signal to a microcontroller that doesn't pull any current on the line and also has an integrated pull-up resistor. Not to be rude but if that doesn't make sense, read up on why we use line pull-up's and how to safely connect one to the switch bank, otherwise you could start causing all kinds of electrical problems.
> 
> This switch isn't going to give you a "pulse" of positive voltage to drive a relay. It's going to take a line that has a normally very weak positive voltage and make it 0 when pressed. Some company out there has to make a relay or FET module that can supply the pull-up voltage and toggle a relay output based on a pull-down switch like this, but I wouldn't know where to start looking...


That's all well and good but it's been done numerous times on Golf R's. The switch banks are the same internally. You're over thinking it. Below is a thread where the guy uses a latching relay to do what he wants. Simple.

OP: Have a look here, it'll probably help you out a lot https://www.vwroc.com/forums/topic/1319 ... ch-button/


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## RobinHelsby (Mar 24, 2018)

RobinHelsby said:


> jonnieb2018 said:
> 
> 
> > I did wonder why some where on he left and ones on the right and if mine was wrongly put in for a RH drive model (drive select on left hand side)
> ...


All this discussion of Drive Select and where the button is to reach it - how many people change it whilst driving? Heck - how many people change it all!!?


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## phazer (Apr 2, 2018)

RobinHelsby said:


> RobinHelsby said:
> 
> 
> > jonnieb2018 said:
> ...


I do sometimes between comfort and individual depending on mood, but I've remapped the * button so no leaning over.


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## WL80 (Jul 10, 2018)

I do sometimes between Auto<>Dynamic<>Individual. Other 2 modes are just distraction anyway...if there was only a way to disable them.
The whole idea of utilizing last slot in this button row did haunt me for some time, a while ago. I intended to rebuild the existing blank to act as a garage door remote controller button. Idea was to have the remote tugged somewhere under the dash, with it's own battery or 12V hook-up and install a microswitch under the blank in question. No need for button light, no limitations on current, all electrically separated from the car / module electronics. That idea is on idle now, as the car is still under warranty and that could be one rather tough thing to explain in case someone at Audi had issues with it.


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## Toshiba (Jul 8, 2004)

cheaper and easier to get the garage link switch in the overhead lamp.


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## WL80 (Jul 10, 2018)

Toshiba said:


> cheaper and easier to get the garage link switch in the overhead lamp.


Retrofiting one is neither cheap nor easy. At least 2 modules plus a harness and programming. That is assuming your RC system is compatible, which is not the case for the garage door I have.


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## phazer (Apr 2, 2018)

WL80 said:


> Toshiba said:
> 
> 
> > cheaper and easier to get the garage link switch in the overhead lamp.
> ...


I was looking at this the other day as I have electric gates and garage doors, it's mega money and like you it doesn't support one of the systems I'd need it to.

What I have thought about doing is getting the switch panel and then wiring the buttons to the buttons on gate/garage remotes. Could be done as battery only or wired in as there is power up there. Maybe worth a go?

Not looked for the part for prices yet, if it's cheap enough I might just buy one and have a go.


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## Toshiba (Jul 8, 2004)

https://www.kufatec.com/de/alle-produkt ... s-fv-41526

English
https://www.kufatec.com/en/all-products ... s-fv-41526

Cost is relative...


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## WL80 (Jul 10, 2018)

phazer said:


> WL80 said:
> 
> 
> > Toshiba said:
> ...


Yeah - that could work. The buttons from the original panel (with 3 buttons) could be isolated with a bit of DIY skills with track isolation and soldering. Used panels can be sourced for min 60€ or so as I checked. 
The way I'll go now is to use the existing RC and have only a hook-up to car's 12V. The remote I have is going heavy on the tiny internal 12V battery and range is bad to almost non-existent in case of colder weather. I attached it before to glass next to the mirror; not obtrusive, but prone to windshield coldness.


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## WL80 (Jul 10, 2018)

Toshiba said:


> https://www.kufatec.com/de/alle-produkte/komplett-set-homelink-garagentoroeffnung-fuer-audi-tt-8s-fv-41526
> 
> English
> https://www.kufatec.com/en/all-products ... s-fv-41526
> ...


Now check what you need besides those buttons and control unit... and see if it works with old coding @ 40MHz.


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## phazer (Apr 2, 2018)

WL80 said:


> Toshiba said:
> 
> 
> > https://www.kufatec.com/de/alle-produkte/komplett-set-homelink-garagentoroeffnung-fuer-audi-tt-8s-fv-41526
> ...


I do agree that the cost is relative but over 600 quid for a remote isn't what I call value for money.

The compatibility is weird, my gate opener operates on 866Mhz but it's not listed as supported, it'd probably still work but not worth taking a punt IMO


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## jonnieb2018 (Nov 15, 2018)

The switch unit arrived today.

It is quite easy to take apart and I will upload pictures later. You can even pull a bar out holding all the buttons in and slide any button out to replace.

I need to work out the circuitry inside and glad of any help.
It might be that I can isolate the switches circuity and then tap into the butto nand pin connector maybe but there may be an easier way but would need some advice if anyone could assist?

Photos will be uploaded later.


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## WL80 (Jul 10, 2018)

Great - show the pictures. If you can freely isolate the switch to make it operate outside the original circuits, the whole task may be simpler and safer.


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## jonnieb2018 (Nov 15, 2018)

phazer said:


> WL80 said:
> 
> 
> > Toshiba said:
> ...


Phazer, I have sourced the homelink parts quote cheap off ebay.de- less than 200 euros could this be an option?

I am going to make the loom up myself.

Mine has both 433 and 868HZ. You can get a converter that will make it work (if it doesn't).

see attached compatibility chart from homelink -compare this to your garage door opener/remote

View attachment homelink_ukenglish.pdf


Here are the photos of switch. I need to trace where the in and output are on the button and which is pin 4


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## macaddict111 (Jun 13, 2018)

That looks a lot easier than I thought it would be, thanks for the photos.

It looks like the two right-side solder leads on the button are not connected to a trace and are there for just mechanical stability. Usually on buttons like that the two top ones are the same contact, two bottom ones are same contact, etc. But it's obviously the two left side contacts you'll want to use. Make sure to totally cut the traces going into those two contacts and you can solder some wire into them. Again, not sure how much current I'd try to flow through that switch. More than a signaling amount (20 mA or so) might work for a while, but not forever...


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## WL80 (Jul 10, 2018)

Nice photos. Job should not be too hard. If you'd like to isolate it, use a knife or precision file to cut tracks connecting to the switch; removal of 0.5-1mm of the track would be enough. I'd use a spot after the test points (exposed, round pads), so you can solder your circuit to those points later.
I suppose you have a multimeter - you can verify the switch action using those pads and later cross-check if isolation/cutting was successful (measure against pads from missing smd resistors - should be open circuit).
If all is fine and checked, secure the soldered cables (not on pads but next to them) with a tiny bit of glue to give it extra stability; I'd recommend UV-curable resin (5s UV glue).


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## jonnieb2018 (Nov 15, 2018)

Thanks Mac & WL for your help but zooming in on the button I'm not sure its both left contacts that are connected.

It looks as though one runs diagonally underneath the button? and the bottom left is connected

Looks like I will have to get my multimeter out and test for continuity when button pressed?

Would it not be possible to use the existing pin though on the main connector as this goes only to the switch doesn't it?
Can I add the momentary switch converter?


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## macaddict111 (Jun 13, 2018)

jonnieb2018 said:


> Thanks Mac & WL for your help but zooming in on the button I'm not sure its both left contacts that are connected.
> 
> It looks as though one runs diagonally underneath the button? and the bottom left is connected
> 
> ...


The diagonal trace you're seeing which goes under the button is for the illumination LED. That's separate, just leave it alone and you'll keep the button illumination.

Do NOT attempt to use the ground/drain/output of the button, as you will DEFINITELY cause problems then. You will essentially be forcing your entire load through the small signal traces for ground which are shared with all the other buttons. This could cause a lot of other problems and the traces won't handle it.

The two traces on the left of the button are clearly the ones you need to use. The safest way to do this is to sever those traces well, leaving the button disconnected from the rest of the board. Then you can put your load's incoming ground to one side of the button, and an appropriate ground connection to the other. That way, the only thing that will get damaged if (and frankly when) you overload the button is the button itself, not a ground trace that's feeding every other button and connected controller.


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## jonnieb2018 (Nov 15, 2018)

macaddict111 said:


> jonnieb2018 said:
> 
> 
> > Thanks Mac & WL for your help but zooming in on the button I'm not sure its both left contacts that are connected.
> ...


Thanks Mac
So i should check with a multimeter over these two contacts and if they are the ones, disconnect the others surrounding or sever them.
Then do i take a new ground wire into one connection of button and output wire to the momentary converter. I suppose I could take the wires (ground in/out) straight out, drill a small hole in the back, rather than trying to connect it to pin 4

Do you know what the 'enables' x3 would be on the converter?
Rgds
JB


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## WL80 (Jul 10, 2018)

It's easy for "Point 1" and respective line cut.
If there is an electrical connection between "Point 2" and "Point 3", the situation is also easy. 
For tracks isolation - cut at marked spots and use Points 1 & 2 for later connection.
If however Point 2 is not connected with point 3, it may be the track from Point 2 goes through to the component marked with Green T above switch. In such case, the upper left pad (2nd terminal of switch), marked as Point 3 goes with "via" to the other side of PCB and there you'd have to look for track to cut. Always check with multimeter. You can still use Point 3 for later connection after the cut.
Before soldering anything on, check if there is sufficient room for new cables as some mechanics could get in a way with module assembly.
Good luck!

Edit: I did not see macaddict111's reply when posting mine, I hope it's not too much confusion 
Edit: in case the point 3 connects to common ground, it could be more difficult to isolate that side without affecting the rest. If you have enough skills with soldering iron, you could temporarily remove the switch and cut the track hidden underneath it, before it connects with "via" that goes to other side where common ground track runs.


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## jonnieb2018 (Nov 15, 2018)

WL80 said:


> It's easy for "Point 1" and respective line cut.
> If there is an electrical connection between "Point 2" and "Point 3", the situation is also easy.
> For tracks isolation - cut at marked spots and use Points 1 & 2 for later connection.
> If however Point 2 is not connected with point 3, it may be the track from Point 2 goes through to the component marked with Green T above switch. In such case, the upper left pad (2nd terminal of switch), marked as Point 3 goes with "via" to the other side of PCB and there you'd have to look for track to cut. Always check with multimeter. You can still use Point 3 for later connection after the cut.
> ...


Thanks WL! that and Macs comments are very helpful. I will have a go over the weekend and see what results I get. If I isolate the whole switch then I can attach the Converter cant I?

I am not sure what the enables x 3 are though on this?

Sorry I forgot to attach the converter diagram

JB










So reading Macs post again (below) the diagonal trace runs under the button,(whether its connected to it or not underneath to the button, I don't know yet) but it must switch on somehow when pressing the button or via somewhere else but would adding a separate ground to the button affect the illumination led and interfere with other components?

_*The diagonal trace you're seeing which goes under the button is for the illumination LED. That's separate, just leave it alone and you'll keep the button illumination.

Do NOT attempt to use the ground/drain/output of the button, as you will DEFINITELY cause problems then. You will essentially be forcing your entire load through the small signal traces for ground which are shared with all the other buttons. This could cause a lot of other problems and the traces won't handle it.

The two traces on the left of the button are clearly the ones you need to use. The safest way to do this is to sever those traces well, leaving the button disconnected from the rest of the board. Then you can put your load's incoming ground to one side of the button, and an appropriate ground connection to the other. That way, the only thing that will get damaged if (and frankly when) you overload the button is the button itself, not a ground trace that's feeding every other button and connected controller. *_


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## WL80 (Jul 10, 2018)

I guess I'd see where your "Local Ground", so common ground line from the switch PCB goes. In case it is exactly the same ground as the GND 2 that you'd use for FOG relay, the thing is really super simple. Only last precaution is to check how much current is drawn by control line from the switch to relay. If it's few milliamperes - then nothing to worry about.
DS is not helping too much here (https://www.abeltronics.co.uk/pdf/FOG-901-FOG-901NP.pdf), I guess it's best to simply measure it using external test.
If above conditions are met - it's a matter of soldering 1 wire and cutting 1 track.

All in all I'd start with multimeter to see where the lines go and check the harness if it's the same ground for the switch array and for the place where you are intending to use relay. Whatever you do, adding some sensitive fuses to your own design never hurts 

In case you are not sure if the ground you have there is the same, the other statement applies fully:
_Do NOT attempt to use the ground/drain/output of the button, as you will DEFINITELY cause problems then. You will essentially be forcing your entire load through the small signal traces for ground which are shared with all the other buttons. This could cause a lot of other problems and the traces won't handle it.
_
In such case both sides of switch should be isolated, with the switch "floating" from the panel GND; you pull then the "GND 2" to that side of switch (see earlier post with getting under the switch).


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## jonnieb2018 (Nov 15, 2018)

Thanks WL

To play it safe (and not damage anything) I will probably end up completely isolating the switch and would the attached be correct, new ground wire in and output to converter?


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## WL80 (Jul 10, 2018)

Looks good, just use the same ground as for the relay. I'm not sure how/if it could help you, but contacts in switch are paired - you could also isolate it, by de soldering/cutting the leg that makes unwanted connection and soldering your new cable to opposite leg, which is electrically the same switch pole. For one with easily accessible track and testing pad, I'd use simple track-cut + soldering to test pad method.


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## jonnieb2018 (Nov 15, 2018)

I see WL, so I can use the opposite connection on other side of switch, keeping well clear of existing connections that I will cut/severe.

thanks for this


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## WL80 (Jul 10, 2018)

https://goo.gl/images/Vi8bAE


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## jonnieb2018 (Nov 15, 2018)

Thanks WL!


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## jonnieb2018 (Nov 15, 2018)

Ok so I had the multi-meter out earlier (and a glass of Moretti beer as well).
 
I have attached some pictures of my findings and some descriptions.

It would appear that the top two points on the switch L & R are the ground points from PIN 11 and are linked underneath the circuit board to a main ring (bottom ground line of Wiring diagram)
The bottom two L & R are the outputs.

The diagonal wire that runs underneath the switch is the positive to the LED (from Pin 14 of main connector) and the negative is linked to the ground circuitry, Pin 11 again.

What I am thinking is I can use Pin 4 of the main connector which runs to the left and right points at the bottom of switch. I can slot in a connector pin within the main connector block to pin 4 and take it to the external momentary converter. I would just need to take only 1 wire to the top pins of the switch. The top two pins being ground and connected to the main ring I am thinking I would have to de-solder away from the main board/ ground loop? alternatively severe/isolate on either side of the switch and solder a wire in between to link them back up??
- here is where I may need some help and this is the tricky bit, isolating the switch from the board -do I de-solder the entire switch or is it easier to sever the line either side and wire and solder a wire in between or a line of solder somehow>?

The LED must be linked to the external module maybe?

JB


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## WL80 (Jul 10, 2018)

I would not touch the wiring loom, only the switch. Did you try try desoldering it?


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## jonnieb2018 (Nov 15, 2018)

WL80 said:


> I would not touch the wiring loom, only the switch. Did you try try desoldering it?


Not yet WL, what temp should I set my soldering iron at and should I remove the whole switch to isolate the ground underneath - probably?


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## WL80 (Jul 10, 2018)

330-350C should be ok. Have some flux on it first.
You can also use wick or a wire trick to lift single legs and reduce risk of PCB damage.


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## jonnieb2018 (Nov 15, 2018)

WL80 said:


> 330-350C should be ok. Have some flux on it first.
> You can also use wick or a wire trick to lift single legs and reduce risk of PCB damage.


Ok so I managed to remove the switch, all good but managed to damage the led so looks like this is going to be an expensive hobby!

I did manage to severe the ground from the switch points -


























I am wondering if I get a switch with the drive select on the right hand side what the pin configurations will be - Presumaby I would need to swap some pins round as the buttons will be on the opposite sides - is there a wiring diagram for this configuration -
JB


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## WL80 (Jul 10, 2018)

That takes care of the GND issue!
As for LED - there is plenty on market, so no worries. In case you have issues getting the same brightness, you can adjust by changing the resistor that is in line with it.
I can also see that the component marked T is gone - was it a fuse?


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## jonnieb2018 (Nov 15, 2018)

Hi WL

It was an orange/red led - again I managed to mess this one up! Tried replacing from another one but messed that up too! (should not have put a 3.5v feed to it - so stupid of me) - so not doing too good here :? .

I have found another switch unit so start again, this time I will get it right! Should I just put some superglue over the ground point to isolate it once I have severed/isolated the contacts?

Proving an expensive modification!

I will take two new wires from the contacts out through the side of the switch unit rather than use the existing points on the main connector block - it will be easier this way and I have worked out a route so they don't get squashed or in the way of any other components.

JB


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## WL80 (Jul 10, 2018)

Sorry to hear you have problems with it, but don't worry about the led's - they are cheap and you can buy them easily on ebay. I suppose Audi module uses one of typical sizes found in the industry. If you find suitable ones and verify their physical and electrical compatibility, I'd replace all to maintain uniform color in the module.
Besides that, some little practice on old PC parts or similar could give you good exercise before getting back to that module...call it damage control 

I'd not use super glue, especially if you'd like to apply some heat next to it - fumes are rather on the evil side.
You could mask it with kapton tape or dedicated masking lacquer / soldering mask. If nothing else even a nail polish could do...just a non-metallic one


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## macaddict111 (Jun 13, 2018)

Looks like you're on the right track jonnieb. I guess I would have just cut the PCB traces with a knife and left the switch soldered on, then soldered wires into the pads. The right-side pads which as you know now are continuous with the left side ones could have been used.


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## jonnieb2018 (Nov 15, 2018)

macaddict111 said:


> Looks like you're on the right track jonnieb. I guess I would have just cut the PCB traces with a knife and left the switch soldered on, then soldered wires into the pads. The right-side pads which as you know now are continuous with the left side ones could have been used.


Hi Mac. I needed to isolate the ground circuit from the switch but the only way to do this wa to remove the switch to reveal the connection underneath. I did think of cutting the ground wire on the reverse side but then I would need to re-route it as it carries on to the next switch.

WL - yes a test board! I am just wondering out of curiosity if the circuitry exists where the blank switches are? (eg in my existing switch). 
Will dig out some nail polish - just hope my other half doesn't ask why I'm borrowing it


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## jonnieb2018 (Nov 15, 2018)

Ok So a bit of a breakthrough tonight! The next console switch unit arrived (hopefully the last) and I discovered that the circuitry is all there, even to the blank button.

The only thing stopping it from being functional is a hard plastic cap and not the compressible rubber piece that the other switches have!

Also the pins are still the same, with DRive Select on the right, this is still Pin 4 etc. I am going to use this unit for my project as Drive select is o the right (on the right side! for my RHD car)

See pictures below.

I just need to get it right this time! 

JB


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## WL80 (Jul 10, 2018)

Cool. You can "copy" the cap in silicone / rubber. Plenty of vids on YT on casting plastics/silicone.
What was the final outcome of your struggle with 1st panel?


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## jonnieb2018 (Nov 15, 2018)

WL, I gave up on the first panel. I think I blew a few LEDs but they were that small, theres no way I would have been able to replace them.
I have removed the switch, soldered wires to the contacts underneath and I will resin the switch down to the board as I would not gave been able to resolder it back down so not quite to plan but this method will still work ok.

Will araldite two part resin adgesive be ok?

JB


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## WL80 (Jul 10, 2018)

I do not know this resin, but most work ok. For small items I use simply a 2 component glue with comparable effect. 
As for installing back the switch, I'm not sure if I follow you here - you'd need to solder it eventually for the electrical contact with pcb...
All in all - take it slow this time and some practice on other electronics may not be a bad idea.
In case soldering is yay and de-soldering is nay, you can also consider macaddict111 approach, where, if I understand correctly, you leave the switch where it is and instead break the lines on both sides of via on the other side of PCB while bridging later the gap (with switch isolated from it) by adding a wire between any parts of circuits left and right from via point you isolated. There is even a neater way of doing that - but I guess too many options is just more confusion at the end


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## jonnieb2018 (Nov 15, 2018)

WL

I have soldered two wires to the switch so that's all I need to do, it will now function as a switch. So I just need to stick it down to the board in the location where I removed it from. Will get some resin later.
It was too intricate to solder the small wires -proving v diffcult and I have big hands -this was my easiest option.
 
JB


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## WL80 (Jul 10, 2018)

jonnieb2018 said:


> WL
> 
> I have soldered two wires to the switch so that's all I need to do, it will now function as a switch. So I just need to stick it down to the board in the location where I removed it from. Will get some resin later.
> It was too intricate to solder the small wires -proving v diffcult and I have big hands -this was my easiest option.
> ...


hehe - I'm 38 now and I have to sadly confirm that the "short hand syndrome" starts on me too. Sadly focusing on close distances is not good as it was.
I'm tinkering with stuff for at least 1/4 century now (you really don't want to know the stuff I built when 12..13, but my old folks could tell ya some stories  ) As a teenager I used to solder some really funky small circuit prototypes, with wires floating in 3d around SOT/MSOP smd packages; called it a spider design lol...now no more :/


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## jonnieb2018 (Nov 15, 2018)

Ha Ha, I have another 9 years on you WL! - I have the t'shirt too (but not as detailed as your childhood!) and I am at a point in my life when I want things to be easier, life to be easier!
I have bought some Gorilla resin off Amazon so should arrive tomorrow.

I have looked at how to remove the unit and its pretty much the same as the radio - removal tools on each side and slide out, unplug the connector....

So to summarise my little experiment...

Xcarlink video input has a rear camera input on it which automatically switches on when there is a power source to it but I am taking it that this is only when the negative and positive are both connected. If it only triggers on positive input then I have another challenge to deal with - so may have to use the console switch as a positive connection but don't like the idea of feeding a 12v supply to a switch which is surrounded by ground connections -what would be another work around. How do I trigger a 12v source when a ground switch is activated?

So in theory:-
When pressing console 'P' switch, this completes the ground circuit to the momentary switch converter, keeping the P switch turned on. The completed circuit triggers the rear camera detection from Xcarlink (but front camera is connected instead as I have the OEM reverse camera) and the front camera image is displayed on the VC with guidelines (guidelines are set within the Xcarlink and can be adjusted).


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## WL80 (Jul 10, 2018)

You could use one of the old logic gates (nand/not would do) or even yet simpler - spdt relay...
All in all a hell lot of effort to get the rev cam working. In simpler cars it was a matter of hooking-up to the break light lead for activation.
edit: in case of gates, you'd need to watch the voltage standard of the chip


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## jonnieb2018 (Nov 15, 2018)

WL thanks,

SPDT relay, where does this go, after the Converter I take it? What would it look like on a wiring diagram hooked up from the momentary converter?

Yes the Camera uses a positive signal to activate (from rear light lamp) or CANbus but I'm using the Xcarlink camera input not for the rear camera but for a front camera (the xcarlink will add with guidelines to the image). I take the car in and out of the garage every day and it is v tight! and having this facility any my gridded garage floor will make it much easier... - I already have the OEM rear camera which I retrofitted and it's great.

Yes a lot of effort but I enjoy it tbh -Let's just say its a hobby and one modification on a long list to do (Homelink, TPMS, power folding mirrors...).


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## WL80 (Jul 10, 2018)

Yeah - I had many mini projects that eventually turned out fat as a whale 
As for the signal, I'm not sure...being tired, maybe I misunderstood you, but the idea was for making the low logic high or reverse. Basically, assuming the signal can drive few miliamps, you feed the active low or high to the relay coil, with other side of coil hooked up to + or - respectively. The contact side you can treat the way you like - one of COM and NO pins would be your out, the other one would go up to - or + depending on desired output level.
In case of low signal power, low space or simple need for more creative tinkering  you can achieve the same in more elegant and compact way with a single transistor (NPN or PNP depending on logic), 2 resistors and maybe a capacitor or two. Downside is lack of isolation you get with relay.
Have fun 

edit - that whole thing is not needed if you apply proper reference potential at the switch...which is "floating" now I assume.


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## jonnieb2018 (Nov 15, 2018)

WL, yes the switch is now floating but I didn't like the idea of having a 12v power source running close to ground sources on the board. I suppose I could always resin over any circuitry under the switch before gluing the switch down.
But now thinking about this, the momentary switch converter uses a ground feed (looking at the wiring diagram) to activate so this messes up the idea of taking a12v directly from the switch? but is the latching output from the momentary switch converter a 12v output in which case this answers all these questions? I will have to check what the output is from the FOG when the switch is activated.

JB


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## WL80 (Jul 10, 2018)

From above circuit I take that you may be over complicating things here a bit. What I'd do is to take same ground as the latching relay is using and have the control cable to the other side of momentary switch. Do you need more? The control input is definitely a low-power circuit, while ground is safe in general. I'm a bit lost now, as I do not see any need for signal change on the diagram.
The button LED is an existing one on PCB, powered as other LED's and requires no logic or PCB change. That is not the LED shown on your diagram of course.


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## jonnieb2018 (Nov 15, 2018)

WL

This is the wiring diagram that is supplied with the momentary switch converter. I would just need to know if the output from this is 12v which would then power the camera feed and trigger the Xcarlink to display on the VC

Not sure what the enables x 3 are on this

The attached is how I see this working but the only area I am uncertain about is if the output is 12 V
when the switch with negative input is pressed.


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## WL80 (Jul 10, 2018)

Do a "dry run" on your workbench, using external power source and a multimeter if you have concerns about switching logic.


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## jonnieb2018 (Nov 15, 2018)

WL I will do,

I have a spare switch will connect up a 12v source from a multi adaptor I have, use the ground to feed the switch and a 12v bulb I have spare and see what happens..Hopefully get the right results or may have to re-think this.

Thanks WL

JB


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## macaddict111 (Jun 13, 2018)

jonnieb2018 said:


> WL, yes the switch is now floating but I didn't like the idea of having a 12v power source running close to ground sources on the board. I suppose I could always resin over any circuitry under the switch before gluing the switch down.
> But now thinking about this, the momentary switch converter uses a ground feed (looking at the wiring diagram) to activate so this messes up the idea of taking a12v directly from the switch? but is the latching output from the momentary switch converter a 12v output in which case this answers all these questions? I will have to check what the output is from the FOG when the switch is activated.
> 
> JB


The fact that they show the diagram with an LED across the switch tells me the FOG will have a pull-up 12V on that line. (You will not have an LED across the switch in your case). As I've said before, the line will either be at 12 V, or you'll short it to ground with the switch, which is the signal the FOG is looking for.


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## jonnieb2018 (Nov 15, 2018)

macaddict111 said:


> jonnieb2018 said:
> 
> 
> > WL, yes the switch is now floating but I didn't like the idea of having a 12v power source running close to ground sources on the board. I suppose I could always resin over any circuitry under the switch before gluing the switch down.
> ...


Hi Mac!

Yes you are quite right, it gives out a 12v output which is what I was looking for.

Pictures attached of nearly complete project, 0V on multimeter, press momentary 'P' switch on console unit and 12V after latching converter kicks in, press again then 0V -all good. 

Drilled a small hole at the back of the casing to feed the wires through.

Just need to solder up some wires and heatshrink some tubing around them.
I needed a 12v cable to run from one of the enables inputs to the 12v input for the converter to work.

Thanks again Mac and WL for all your help! The next step will be to test it in the car with the Xcarlink hooked up and front camera.


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## jonnieb2018 (Nov 15, 2018)

and here is the converter all boxed up and ready. just need to find some space for the xcarlink box, wifi box and this. I thought of a custom holder/box within the glove box (under the MMI)but ideally want to be able to tuck it out of sight. Maybe ~I will find some space behind the console switch

Anyone know where I can find some space behind the dash?


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## WL80 (Jul 10, 2018)

Not sure about RHD car, but there is a bit of room under each side panel and next too fuse panel as well in my car.


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## jonnieb2018 (Nov 15, 2018)

Thanks WL.

the xcarlink - links to the MMI unit but the LCD cable is only 300mm long so this will have to go fairly close the MMI, not sure if there is space behind the mmi or I can cut a slot at the back of the mmi holder for it. - I really need to take the glove box out to check.
the other devices can go anywhere. I think there may be some room behind the console switch but not sure until I take it out.


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## VorsprungDur (Apr 6, 2018)

jonnieb2018 said:


> Thanks WL.
> 
> the xcarlink - links to the MMI unit but the LCD cable is only 300mm long so this will have to go fairly close the MMI, not sure if there is space behind the mmi or I can cut a slot at the back of the mmi holder for it. - I really need to take the glove box out to check.
> the other devices can go anywhere. I think there may be some room behind the console switch but not sure until I take it out.


Amazing work, looking forward to seeing it all up and running.


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## jonnieb2018 (Nov 15, 2018)

Thanks Vorsprung, hopefully it will work out well.
I think the challenge will be finding how I get a cable from the front of the car to behind the dash as I gave no idea where the cable routes/access through the firewall are

JB


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