When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The VW/Audi solution that people see is simply a VW switch (which is wholly unnecessary since we have a home function position) with a little logic board that turns on the low beams when the light sensor senses low light and the switch is in the home/auto position. If Porsche didn't use ground side switching ,we could use our switch and simply use that little harness they include with the light sensor. Since we do use ground side switching, we can't use it. However, it is a VERY easy circuit to reproduce. I was originally going to use an Arduino board to do it since it's basic logic, but since it's 12V it'd be kind of a hassle and cost more than necessary.
So I purchased a $9 photosensitive relay on Amazon and got it to work today. The wiring is a little tricky because there is no constant 12V and you don't want the board sucking power when the car is turned off. So I wired the board to use the 12V source (only when iginition is on) and used the Home position as the ground. Remember, Home off means it's 12V and on means it's ground. So the board will only turn on when the car is on and HOME is engaged. Then it's simply a matter of connecting the relay to the ground (pin 6) and low beams (pin 1).
I personally wired in a harness so I wouldn't have to tap into the OEM wires, so it cost a bit more than $9 (just for the cost of a cable).
Functionally, it works pretty well. Any other position than home, it works completely normally. The relay is off and nothing is affected. When in home and ignition is on, the relay is energized and turns on the low beams when the light sensor doesn't sense enough light. I routed the sensor to near the climate control light sensor so it's barely visible.
Oh, I also did the DRL hack on my harness and everything works as it should. Home function still works fine. Fog lights still work fine. It works exactly like a factory auto headlight solution.
Interior view. Basically impossible to see from normal seating position. Exterior view. Oops, must have scratched the trim placing it with tweezers. I still need to get an enclosure. Right now i have it wrapped up with tape.
When it starts to get dark you turn on the lights. When you turn car off you shut off lights.
I coulld never understand having auto-lights - I never use them in my Mercedes SUV, my wife never uses them in her Mercedes sedan.
Why would you want them in a Porsche?
Are people that forgetful and poor eyesight not to see that lights weren't turned off when turning off car??
I would rather delete my power seats. That’s a real performance rob and I prefer quick manual adjustments over slow motors.
Auto headlights add zero weight. Our cars have all the hardware necessary to have auto lights, they just didn’t put the software in the modules. I don’t like the auto on, but I do like the auto off.
Auto headlights is not a luxury feature nor does it have anything to do with performance (negative or positive). It’s just a creature comfort.
I’m also a tinkerer. I like doing my own maintenance. Adding in modifications that require thinking is fun for me. Auto headlights is not a big deal, but it’s something I knew I could do so I did it.
When it starts to get dark you turn on the lights. When you turn car off you shut off lights.
I coulld never understand having auto-lights - I never use them in my Mercedes SUV, my wife never uses them in her Mercedes sedan.
Why would you want them in a Porsche?
Are people that forgetful and poor eyesight not to see that lights weren't turned off when turning off car??
The VW/Audi solution that people see is simply a VW switch (which is wholly unnecessary since we have a home function position) with a little logic board that turns on the low beams when the light sensor senses low light and the switch is in the home/auto position. If Porsche didn't use ground side switching ,we could use our switch and simply use that little harness they include with the light sensor. Since we do use ground side switching, we can't use it. However, it is a VERY easy circuit to reproduce. I was originally going to use an Arduino board to do it since it's basic logic, but since it's 12V it'd be kind of a hassle and cost more than necessary.
So I purchased a $9 photosensitive relay on Amazon and got it to work today. The wiring is a little tricky because there is no constant 12V and you don't want the board sucking power when the car is turned off. So I wired the board to use the 12V source (only when iginition is on) and used the Home position as the ground. Remember, Home off means it's 12V and on means it's ground. So the board will only turn on when the car is on and HOME is engaged. Then it's simply a matter of connecting the relay to the ground (pin 6) and low beams (pin 1).
I personally wired in a harness so I wouldn't have to tap into the OEM wires, so it cost a bit more than $9 (just for the cost of a cable).
Functionally, it works pretty well. Any other position than home, it works completely normally. The relay is off and nothing is affected. When in home and ignition is on, the relay is energized and turns on the low beams when the light sensor doesn't sense enough light. I routed the sensor to near the climate control light sensor so it's barely visible.
Oh, I also did the DRL hack on my harness and everything works as it should. Home function still works fine. Fog lights still work fine. It works exactly like a factory auto headlight solution.
Interior view. Basically impossible to see from normal seating position. Exterior view. Oops, must have scratched the trim placing it with tweezers. I still need to get an enclosure. Right now i have it wrapped up with tape.
This is a great solution!! I'm going to do this on my car!
When it starts to get dark you turn on the lights. When you turn car off you shut off lights.
I coulld never understand having auto-lights - I never use them in my Mercedes SUV, my wife never uses them in her Mercedes sedan.
Why would you want them in a Porsche?
Are people that forgetful and poor eyesight not to see that lights weren't turned off when turning off car??
I would rather delete my power seats. That’s a real performance rob and I prefer quick manual adjustments over slow motors.
Auto headlights add zero weight. Our cars have all the hardware necessary to have auto lights, they just didn’t put the software in the modules. I don’t like the auto on, but I do like the auto off.
Auto headlights is not a luxury feature nor does it have anything to do with performance (negative or positive). It’s just a creature comfort.
I’m also a tinkerer. I like doing my own maintenance. Adding in modifications that require thinking is fun for me. Auto headlights is not a big deal, but it’s something I knew I could do so I did it.
Very tempted to try that also, for the same reasons you mentioned. Thank you for sharing!
Would you mind sharing also the link to the sensor so I know where to start from? Did the board we see in the pic come with the sensor?
One thing I keep wondering is: is there a way to tap into the sensor that is already present on the car which lights up the dash when lights are on and it detects low luminosity...
My only annoyance is jumping from car to car where some have it and some don't or when you get a safety inspection and the tech messes around with the lights and doesn't put them back to the original setting.
I would rather delete my power seats. That’s a real performance rob and I prefer quick manual adjustments over slow motors.
Auto headlights add zero weight. Our cars have all the hardware necessary to have auto lights, they just didn’t put the software in the modules. I don’t like the auto on, but I do like the auto off.
Auto headlights is not a luxury feature nor does it have anything to do with performance (negative or positive). It’s just a creature comfort.
I’m also a tinkerer. I like doing my own maintenance. Adding in modifications that require thinking is fun for me. Auto headlights is not a big deal, but it’s something I knew I could do so I did it.
I get it - It's great that you can do these upgrades yourself. Something I never got into myself.
When I was younger I tinkered on 356's and early 911's but those days are gone.
These cars are much more sophisticated, not as simple
When it starts to get dark you turn on the lights. When you turn car off you shut off lights.
I coulld never understand having auto-lights - I never use them in my Mercedes SUV, my wife never uses them in her Mercedes sedan.
Why would you want them in a Porsche?
Are people that forgetful and poor eyesight not to see that lights weren't turned off when turning off car??
if every other car you've owned for the past decade has had automatic headlights you no longer have the routine of turning them on and off yourself. you stop thinking about it. sure you think to turn them on because it's dark and you can't see. but it's the turning them off that will get you. if you park in a well lit garage that lights up when you open your door, you don't see that you left your lights on.
within my first two months of 997 ownership i left my lights on in the garage. battery died. the next day i then learned the fun process of opening the motorized frunk with a dead battery. it was not a pleasant experience considering i needed to be somewhere with the car.
Very tempted to try that also, for the same reasons you mentioned. Thank you for sharing!
Would you mind sharing also the link to the sensor so I know where to start from? Did the board we see in the pic come with the sensor?
One thing I keep wondering is: is there a way to tap into the sensor that is already present on the car which lights up the dash when lights are on and it detects low luminosity...
I’ll take some more detailed photos and step by steps this weekend (out at the moment). That’s a good point about the gauge cluster light sensor. However, because of location, it’s probably better to use the climate control light sensor. I’m just trying to do some research to see if two resistance measurements can be made on the same photo resistor so it doesn’t impact the climate control.
I’ll take some more detailed photos and step by steps this weekend (out at the moment). That’s a good point about the gauge cluster light sensor. However, because of location, it’s probably better to use the climate control light sensor. I’m just trying to do some research to see if two resistance measurements can be made on the same photo resistor so it doesn’t impact the climate control.
Thanks for the reply and link. Definitely interested in more details about how to do it, very kind!
I didn't realise climate control and dash were relying on separate sensors, I guess whichever works (and your solution is also more than satisfactory).
I am amazed how many people drive at dusk or rain in a dark colored car with no headlight/driving lights on. In the old days we would flash our lights to remind them to turn lights on. But today with cell phones that they are screwing with they are distracted! Auto lights make scent! That's my 2 cents!
With the advent of DRLs too many drivers think their headlights are on when they’re not. That’s not a problem to me in the 997 but kudos to the OP for engineering this. I made my lady friend promise me that her next car will have auto lights.
I am amazed how many people drive at dusk or rain in a dark colored car with no headlight/driving lights on. In the old days we would flash our lights to remind them to turn lights on. But today with cell phones that they are screwing with they are distracted! Auto lights make scent! That's my 2 cents!
That was exactly I was going to note. I drive to my work very very early in the morning, before sunrise, and a LOT of cars on the road and highway are with headlights turned off (specially mostly those Japanese brands (and lower trim levels), as Toyotas, Hondas, Mazdas, etc). A lot of people seems still asleep (at some degree) and the wrong thing is that the inside instrument cluster is automatically illuminated all time, BUT not the headlights. People didn't realize to turn on manually. A big issue, that should be solved easily with the obligation to use that photocell. (As they did with the backup cameras).
Last edited by FlatsixS; Aug 20, 2023 at 06:28 AM.
Talos Takes Your 991 Porsche 911 GT3 to the Next Level for a Cool $1.13 Million
Slideshow: Talos Vehicles has transformed the Porsche 911 GT3 RS into a carbon-bodied, race-inspired machine that costs well over $1 million before the donor car is even included.
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Slideshow: Long before engineering consulting became trendy, Porsche was quietly helping other automakers build everything from supercars to economy hatchbacks.
9 Features and Characteristics That Only Porsche People Understand
Slideshow: Some brands build cars. Porsche builds traditions, obsessions, and a few habits that stopped making sense decades ago but somehow became part of the charm.
This Builder Is Turning Heads With Its Slantnose 911 Creation
Slideshow: A small Polish tuner has reimagined the Porsche 911 Slantnose for the modern era, blending 1980s nostalgia with widebody tuning culture and serious performance upgrades.
Porsche 911 GT3 Artisan Edition Pays Homage to Japanese Culture
Slideshow: Porsche has created a Japan-only 911 GT3 Artisan Edition that blends track-ready hardware with design cues inspired by traditional Japanese craftsmanship.
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Slideshow: Porsche's latest electric Cayenne Coupe blends dramatic styling with supercar acceleration, turning the brand's midsize SUV into a 1,139-horsepower flagship.
$9 solution for automatic headlights
