Question About Coding Front Fog Light Button

[jmciver]

Ok, everybody obviously knows that the F8X does not have front fogs. However, the switch can still be modified to function with some coding and by trimming some tabs on the button so that it actually operates as a button and not a "blank" as it comes from the factory. There are some that have coded the button to turn on "LED Fogs" as well - but this thread is not about that mod.

Also many, including myself, have done a similar mod with the stock light switch and coded rear fogs, using the bottom button. IIRC, the coding for the rear fogs is two basic parts:

1) To turn on the light in the cluster that will tell you when the rear fogs are on/off (this is one specific parameter that must be changed in the cluster module)

2) To send the signal to the Rear Electronics Module (REM) to actually turn on the rear fogs (this is another specific parameter that must be changed in the REM IIRC)

So my question is, what is the coding to allow the front fog light button to turn on the front fog light indicator in the cluster? Since we don't have fog lights installed in the F8X, I don't need any coding that talks to the Front Electronics Module (FEM), only the coding that talks to the cluster to turn on that front fog light indicator light.

Why am I interested in this? I am thinking about using a CAN BUS interface to re-purpose the unused fog light button as a kill switch for an accessory I want to add in the near future (instead of using a toggle switch installed in the dash or center console - not a fan of that for aesthetic reasons). I would like to use the front fog light indicator in the dash to know the current status of the accessory - off or on. The light in the cluster is not necessary for the button to work with coding (the coding I found for the front LED Fogs mod does not turn on the fog light indicator light in the cluster). But I think it would be a nice touch for what I am trying to accomplish.

[jmciver]

Ok, I guess I will re-phrase the question a bit since I recognize that what I am asking for help with is a bit out of the ordinary for the F8X crowd since we don't have front fogs or use that front fog button (with the exception of the few that have done the LED fog light mod). So for those of you with coding diagnostic experience (i.e. familiarity with software versions, comparing CAFD files, comparing I-Steps, etc), how about this....

Can you compare the appropriate CAFD files/software from a 2017 F80 M3 (which does not have front fog lights) to a 2017 F3X 3-series (with front fog lights) to see which might be the coding parameter(s) that are different that would possibly correspond to the front fog light button, specifically activating the fog light indicator in the cluster? I would give it a try, but I don't have access to any software from an applicable F3X with front fogs.

I still have some more research to do regarding the CAN bus portion with the button. I will have a CAN bus sniffer soon to do some testing with buttons in the car. ISTA-D provides all of the wiring diagrams needed so I know where all of the CAN bus tap points are in the car. And the hardware/electronics to interface with the CAN bus in the car to make this work is readily available using inexpensive DIY electronics. If this works the way I think it will, I am sure other F8X owners with "gadgets" in their car would love to use an OEM button for control of the gadget (instead of an unsightly toggle switch somewhere on the dash) to have a nice integrated look.

[milk242]

Most likely the switch is a momentary switch so you could just find the pins that triggered by the closing of the contact and connect a relay to switch on/off your accessory

[jmciver]

Originally Posted by milk242

Most likely the switch is a momentary switch so you could just find the pins that triggered by the closing of the contact and connect a relay to switch on/off your accessory

You are correct, it is a momentary “switch” but it is attached to a circuit board, like most of the buttons in modern cars. Soldering wires to the circuit board would be a PITA IMHO. Going through the CAN bus is a cleaner solution, even though there is currently no off the shelf product to do it....

[milk242]

I meant that the plug on the back probably doesn’t have wires attached to all the pins on the fog light/headlight switch so you could probably just find the same pin connectors online and make your own wires and plug it into the free spaces on the plug without soldering. This was what I use to do on my Audi for a kill switch for my laser jammer.

Edit:
Thinking about you saying that you can code the fogs in probably means the pins are already occupied.

[jmciver]

Originally Posted by milk242

I meant that the plug on the back probably doesn’t have wires attached to all the pins on the fog light/headlight switch so you could probably just find the same pin connectors online and make your own wires and plug it into the free spaces on the plug without soldering. This was what I use to do on my Audi for a kill switch for my laser jammer.

Edit:
Thinking about you saying that you can code the fogs in probably means the pins are already occupied.

Doesn't work that way in modern cars now. Pretty much all of the buttons/switches in the car don't work that way as they are not connected directly to the component (i.e. light, window, etc.) and the battery to directly switch power. The buttons/switches communicate via the CAN Bus between the different ECUs in the car that control the various components. Each button has it's own address. If you know the address of the button, you can control other things like external relays, etc using DIY electronics available to "Hack" the CAN bus.

[CanAutM3]

Originally Posted by jmciver

So my question is, what is the coding to allow the front fog light button to turn on the front fog light indicator in the cluster?

Tough luck, there is no "front fog light" icon indicator light in the F8X instrument cluster.

[jmciver]

Originally Posted by CanAutM3

Tough luck, there is no "front fog light" icon indicator light in the F8X instrument cluster.

Well that is unfortunate - and the first time I have heard that. I would not think the various indicator LEDs in the cluster would be different between the different cars in the 3/4-series. Did you verify that with a cluster lamp test using E-sys or something?

Not a deal killer though since I know the button will send a CAN bus signal, as I temporarily coded the front LED fogs for a short while.

[CanAutM3]

Originally Posted by jmciver

Well that is unfortunate - and the first time I have heard that. I would not think the various indicator LEDs in the cluster would be different between the different cars in the 3/4-series. Did you verify that with a cluster lamp test using E-sys or something?

Not a deal killer though since I know the button will send a CAN bus signal, as I temporarily coded the front LED fogs for a short while.

The F8X instrument clusters are indeed different than the F3X ones.

If you look at the cluster in a specific lighting, you can see what indicators are available. And the front fog definitely is not there. Which makes sense, since there is no F8X anywhere in the world that has front fog lights .

[jmciver]

Originally Posted by CanAutM3

The F8X instrument clusters are indeed different than the F3X ones.

If you look at the cluster in a specific lighting, you can see what indicators are available. And the front fog definitely is not there. Which makes sense, since there is no F8X anywhere in the world that has front fog lights .

Most definitely makes sense, but many times car manufacturers will share components like these between models to save money, which is what I was hoping for.... Oh well, not the end of the world. I still like the fact that there are two "factory" unused bottons available that will hopefully work with what I am trying to do to have a clean look when adding aftermarket accessories. I have added aftermarket accessory switches/buttons to my cars in the past - but my OCD never completely liked it .

[Zermatt]

Thats too bad, I too am planning on using the the front fog switch on an accessory and hoped to have the corresponding instrument cluster indicator light up. I was planning on tapping the +12v output from the FEM to turn on my accessory (w coding).

[jmciver]

Originally Posted by Zermatt

Thats too bad, I too am planning on using the the front fog switch on an accessory and hoped to have the corresponding instrument cluster indicator light up. I was planning on tapping the +12v output from the FEM to turn on my accessory (w coding).

If my CAN Bus approach works, you might want to consider using the CAN Bus method. Taping the right 12v FEM output may in theory work, but the electronics in these cars is pretty finicky. Taping off the 12v line you need could cause a voltage drop which could cause a fault someplace....

[Professor///M]

Originally Posted by jmciver

Ok, everybody obviously knows that the F8X does not have front fogs. However, the switch can still be modified to function with some coding and by trimming some tabs on the button so that it actually operates as a button and not a "blank" as it comes from the factory. There are some that have coded the button to turn on "LED Fogs" as well - but this thread is not about that mod.

Also many, including myself, have done a similar mod with the stock light switch and coded rear fogs, using the bottom button. IIRC, the coding for the rear fogs is two basic parts:

1) To turn on the light in the cluster that will tell you when the rear fogs are on/off (this is one specific parameter that must be changed in the cluster module)

2) To send the signal to the Rear Electronics Module (REM) to actually turn on the rear fogs (this is another specific parameter that must be changed in the REM IIRC)

So my question is, what is the coding to allow the front fog light button to turn on the front fog light indicator in the cluster? Since we don't have fog lights installed in the F8X, I don't need any coding that talks to the Front Electronics Module (FEM), only the coding that talks to the cluster to turn on that front fog light indicator light.

Why am I interested in this? I am thinking about using a CAN BUS interface to re-purpose the unused fog light button as a kill switch for an accessory I want to add in the near future (instead of using a toggle switch installed in the dash or center console - not a fan of that for aesthetic reasons). I would like to use the front fog light indicator in the dash to know the current status of the accessory - off or on. The light in the cluster is not necessary for the button to work with coding (the coding I found for the front LED Fogs mod does not turn on the fog light indicator light in the cluster). But I think it would be a nice touch for what I am trying to accomplish.

I thought of this too. I wanted to hardwire a radar detector and make the top fog light button the kill switch. I don't know that it's possible as an end user... maybe if you had a very strong coding and or electrical engineering background you could figure it out

[jmciver]

Originally Posted by JSTDR1V

I thought of this too. I wanted to hardwire a radar detector and make the top fog light button the kill switch. I don't know that it's possible as an end user... maybe if you had a very strong coding and or electrical engineering background you could figure it out

Actually, it should be very doable using a programmable CAN bus interface. You are right that there is no ready made product that does what I want to do - at least not that I could find. But I have already found info on the net where people have used the CAN bus inside a car to control aftermarket accessories.

For stage one of this project I recently bought a cheap CAN bus sniffer and tapped into the CAN bus in the car and was able to identify the CAN Bus ID for the two fog light buttons with my laptop. Next step is building and programming the CAN Bus interface, which is surprisingly cheap (< $50) and only requires some basic soldering skills.

I stumbled across the video below which is what gave me this idea to try this project...

https://www.youtube.com/watch?v=YK2GefWiG4w