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I started by disassembling one of the VW automatic headlight retrofit kits that I had from an old Jetta. It works on a very similar principle, but the VW switch appears to be opposite in that all of the signal pins are ground and it uses the 8th pin as a positive voltage. It even has the same connector and pinout for all of the functions.
Yeah, that's right. For some reason VW decided to have "active 12V" while Porsche has "active ground".
I think what Porsche chose is a little bit niftier, as it doesn't need both battery and ignition power.
But the drawback is that even though the Porsche and VW hardware LOOKS the same, from an electrical standpoint it isn't.
Yeah, that's right. For some reason VW decided to have "active 12V" while Porsche has "active ground".
I think what Porsche chose is a little bit niftier, as it doesn't need both battery and ignition power.
But the drawback is that even though the Porsche and VW hardware LOOKS the same, from an electrical standpoint it isn't.
I would definitely recommend anyone who isn't technically inclined (or just doesn't want to deal with it) to get Hatzenbach's solution. We talked a bit offline and I can tell you it's well made and should be reliable.
I think I will leave the fog light LED out of my setup, but it is a good idea to have some sort of indicator. Same for the "HOME" function, as I already have mine programmed the way I like with the fog lights through PIWIS.
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I started by disassembling one of the VW automatic headlight retrofit kits that I had from an old Jetta. It works on a very similar principle, but the VW switch appears to be opposite in that all of the signal pins are ground and it uses the 8th pin as a positive voltage. It even has the same connector and pinout for all of the functions.
Were you able to disable the fog lights coming on for the home function? I like the parking lights coming on, but not the fog lights.
I also started with the retrofit kit and realized the switch is just a switch. The logic is all handled on the small controller in the add-on. Ideally, I think it'd be best to make something with an ATTiny85 if I'm going with a PCB. Otherwise, simply wiring in the diodes in line with the harness, using a stripboard, or a project board with jumper wire is wholly sufficient. I'm just trying to get the solution as small as possible and it's really just for fun. If I end up doing the ATTiny85 project, I'll let you know. I'm planning on also trying to make another device to control the Sport Chrono clock and might just combine all this into one module.
Yeah @funnelofdoom and I keep communicating and exchanging ideas. I think @funnelofdoom 's solution is more for the DIY oriented person and mine caters more to the one who wants plug & play.
Just a quick update, the auto headlight switch from the Cayenne does work, but mine came with amber backlighting. So I swapped out the internals and used the housing from the Cayenne with the internals of my 997.1 and that squared things away. The nice thing about the Cayenne switch is that the auto is lit in green until the lights turn on, which then turns it back to the backlight color. I'm not sure if that's because of my circuitry or if that's how it's supposed to act.
I'm assuming it's because of my circuitry though because I'm triggering the headlights from the switch. I'm sure cars made with the auto function trigger the lights via the front control module. I haven't yet integrated the OEM sun sensor into my solution, but will when I pull out the panels for my upcoming PCCM+ install. I prefer to pull interior panels out as little as possible as old plastic parts seem to lose their tolerances fairly easily.
Last edited by funnelofdoom; 12-21-2023 at 03:22 AM.
Were you able to disable the fog lights coming on for the home function? I like the parking lights coming on, but not the fog lights.
I also started with the retrofit kit and realized the switch is just a switch. The logic is all handled on the small controller in the add-on. Ideally, I think it'd be best to make something with an ATTiny85 if I'm going with a PCB. Otherwise, simply wiring in the diodes in line with the harness, using a stripboard, or a project board with jumper wire is wholly sufficient. I'm just trying to get the solution as small as possible and it's really just for fun. If I end up doing the ATTiny85 project, I'll let you know. I'm planning on also trying to make another device to control the Sport Chrono clock and might just combine all this into one module.
I have a 987.1 Cayman S which has halogen fog lights and purposely enabled them in PIWIS. The parking lights are in the same housing on the 987.1, just a much dimmer bulb than the fogs and much more prone to burning out. I've had to replace the parking light bulbs every couple years now.
I just installed my Cayenne switch and noticed the amber lighting as well. I will have to take them apart and see what I can swap between the two as well. The final solution for the sensor placement for me may be a little 3D printed stem to hold it in the defroster vent over having it visible on the surface of the dash.
EDIT: Also looking at doing a PCCM+ in the spring for similar reasons. Plastic panels do not like to be pulled in midwestern winters without something breaking.
I have a 987.1 Cayman S which has halogen fog lights and purposely enabled them in PIWIS. The parking lights are in the same housing on the 987.1, just a much dimmer bulb than the fogs and much more prone to burning out. I've had to replace the parking light bulbs every couple years now.
I just installed my Cayenne switch and noticed the amber lighting as well. I will have to take them apart and see what I can swap between the two as well. The final solution for the sensor placement for me may be a little 3D printed stem to hold it in the defroster vent over having it visible on the surface of the dash.
EDIT: Also looking at doing a PCCM+ in the spring for similar reasons. Plastic panels do not like to be pulled in midwestern winters without something breaking.
Swapping internals is super easy. The circuit board of the switch is secured by very loose plastic tabs. There are no tamper stickers. There are no harnesses or wires, either. Just carefully take out the circular PCB while pushing in the black plastic tabs. Completely swappable with each other.
Just added a green status LED to my Cayenne auto headlight switch. I figure i have the stock switch for picky buyers anyway so am just doing whatever with the auto labeled one. If anyone is interested, you can just wire in a small green LED and tie it to pins 4 and 1 directly on the PCB for the light switch with thin wiring with a pull up resistor and/or diode (this is necessary for many reasons). Pin 4 would be the cathode end and pin 1 would be the anode end. Now whenever the low beams are activated (by the auto circuit or by manually pulling the switch), the little low beam indicator will turn green.
Just added a green status LED to my Cayenne auto headlight switch. I figure i have the stock switch for picky buyers anyway so am just doing whatever with the auto labeled one. If anyone is interested, you can just wire in a small green LED and tie it to pins 4 and 1 directly on the PCB for the light switch with thin wiring with a pull up resistor and/or diode (this is necessary for many reasons). Pin 4 would be the cathode end and pin 1 would be the anode end. Now whenever the low beams are activated (by the auto circuit or by manually pulling the switch), the little low beam indicator will turn green.
That's a nice addition: with the auto headlights I've wanted a more obvious headlight indicator. Can you give some more details? The resistor would just go in series with the LED to drop the voltage, right?
If you have any specific components or resistor values etc. that work that would be helpful: I'm pretty good at fixing electronics but my circuit design skills are super basic.
Yes, in series (but in theory it's limiting current). Also add a diode because depending on your resistor, you could technically blow the LED in certain situations when the headlights are off. You could do something like this but with different values for the resistor. It doesn't really matter what diode you use for this application but start with about a 5kohm resistor. Disregard values here. This is just to show a diagram.
12-15-2023, 07:08 PM
