# Do ALL Eos vehicles come with a light sensor? Where is it?



## Shaka (May 20, 2001)

As many of you know, there are TWO options for European Headlight switches. There is a typical switch that adds a new position (instead of off/on, there is a parking light option). But there is another switch that adds an AUTO position.
If you have a Mk5-platform car that does NOT have the light sensor, and you install this variation of the switch (or a USA-based switch with Auto), the lights basically are ALWAYS on whenever the car is on. However if your car has a light sensor, it uses that to of course determine when the lights should be on.
My question is.. for a non-comfort or non-sport equipped 2.0T DSG Eos, did they still install the light sensor? Or is that the same sensor as the rain senser, which is located in the windshield (which our car def doesnt have). Anyone know!?


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## aflaedge (Jun 27, 2006)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

I believe there are also light sensors on the front and back of the rear view mirror. I don't know if they are tied into the same system though.


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## just-jean (Sep 14, 2006)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (aflaedge)*

would be nice if the sensor is there and we just need the switch and a little software to tell it what to do


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

Yeah I knew there was a sensor for the auto dimming mirror, that is usually in the face of the mirror. But it seems unlikely that would be the same sensor for the headlights. You'd want a more 'exterior' based sensor for that.
But that outside sensor is probably incorporated into the rain sensing aspect of the car, where I know the sensor is on the windshield-side of the rear-view mirror, against the glass. I just dont know if thats the rain sensor only, or the rain AND the light sensor. IF the latter, then the AUTO position on an Eos would be the same as "always on" -- except that it would allow coming home / leaving home features, and would turn the lights off with the car for you too.


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## gilesrulz (Nov 2, 2006)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

I think the inch square sensor down by the windshield is the light sensor. I say this only because I had a Volvo with automatic lights (but no automatic wipers) that had a sensor in the same position.


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (gilesrulz)*


_Quote, originally posted by *gilesrulz* »_I think the inch square sensor down by the windshield is the light sensor. I say this only because I had a Volvo with automatic lights (but no automatic wipers) that had a sensor in the same position.

I think that is the Sat-Radio Antenna, because if you look at the rest of the car there is no sign of an antenna elsewhere, and that is about the same size as the aftermarket Terk antennas I've had on previous cars. I should probably consult the manual but its the wife's car so she has the book. You may be right, but... I dunno. I think that black piece is the sat ant but who knows


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## aflaedge (Jun 27, 2006)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

The sat antenna is in the trunk lid. Somewhere in this forum there is a pretty good picture of the construction of the trunk.


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## gilesrulz (Nov 2, 2006)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

Actually, when it cools down at night you can clearly see the sat antenna (as well as the others) throught the trunk lid because it will collect dew before the rest of the trunk.


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (aflaedge)*


_Quote, originally posted by *aflaedge* »_The sat antenna is in the trunk lid. Somewhere in this forum there is a pretty good picture of the construction of the trunk.

Found it...








Based on that, the dash plastic piece does seem a more logical place for the Light Sensor. Based on that, I think I am going to try to retrofit (from ECS Tuning) the coming-home feature with a european headlight switch.
This will give us OFF, AUTO, PARKING and HEADLIGHTS as the 4 options. And when in AUTO, should also allow Coming Home (which will require some VAG tricks obviously).
More info to come then... yay!


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## Pelican18TQA4 (Dec 13, 2000)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

The light sensor is integrated into the rain sensor on the windshield. The plastic sensor on the dashboard is part of the Climatronic system, it measures the intensity of the sun and adjusts the climate control accordingly. MkIV cars with Climatronic have the same sensor.


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## PanEuropean (Nov 3, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (aflaedge)*


_Quote, originally posted by *aflaedge* »_I believe there are also light sensors on the front and back of the rear view mirror. 

If there are light sensors on the front and back of the mirror, those control the mirror auto-dimming (auto darkening) feature only, if that feature is provided.
If a light sensor is installed in the vehicle for the purpose of controlling 'automatic headlight control', it will be integrated into the rain-sensor. In other words, there are two types of rain-sensors in the VW world, one that senses rain only, and one that senses both rain and light.
I recently participated in a retrofit of a 'rain and light sensor' to a European Phaeton that was only equipped with the rain sensor when it was built. In the process of doing this retrofit, we replaced the original rainsensor with a rain and light sensor, and replaced the original lightswitch with one that had the 'automatic headlight control' position. Replacing the rain sensor ranks right up with a heart transplant so far as the risk of screwing things up is concerned... if you don't know exactly how to remove and replace it, you will bust it (this is guaranteed in writing), plus, you need a special lubricant - kind of like a petroleum jelly - to ensure that there are no air bubbles between the forward face of the sensor and the inside part of the glass.
Even with all that screwing around, replacing the parts, etc., we still have unresolved coding difficulties - the automatic light sensor now works (although we had to change roof controller coding to support that), but the rain-sensor does not work anymore.
I guess what I am trying to say is that retrofitting a light sensor is a heck of a lot more complex that you might think it to be.
Michael


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## PanEuropean (Nov 3, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (PanEuropean)*

Here's a bit more info about rain-sensors - again, Phaeton specific, but it's the best I can do. 
Rain Sensor Wipers.
By the way, I have zillions of pictures of how to change out a rainsensor, in case anyone ever wants to do it - but like I said before, I wouldn't rush into this project. The parts are expensive (several hundred bucks), and there are coding issues that need to be dealt with - more than simply indicating that a light-sensor is installed.
Michael


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (PanEuropean)*

Thanks for the very informative replies, Michael. This doesnt technically answer my question as far as Eos-specific applications go, however.
Based on the info you have for a Phaeton, do you feel that chances are likely that the Eos does NOT already have a light sensor? Or do you think that there is a chance it does?
Rumor has it that many Mk5 vehicles that did NOT come with rain sensing wipers DID come with the Light Sensor, which allows a retrofit of the Automatic Headlight Switch without any issues (maybe a VAG recode but that is it). The whole point of this thread was to determine where the Eos' light sensor is, etc.
So I guess what I am saying is that I can tell you for certain our mirror is NOT auto dimming and we do NOT have the rain sensor (you can tell by looking at the mirror and the sensor that would sit against the windshield). But that doesnt tell me about the Automatic Headlights and the Light Sesnor it requires ... or based on your wisdom, you concede its non-existant since on other cars, its located in the same mirror-cavity?!


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## PanEuropean (Nov 3, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*


_Quote, originally posted by *Shaka* »_The whole point of this thread was to determine where the Eos' light sensor is...

If the Eos has a rainsensor or a lightsensor-rainsensor combination (where the lightsensor is used for automatic headlight control), I am 99.9% certain that it will be located on one side or another of the interior rear view mirror. That is the practice followed with every other VW product - Phaeton, Touareg, Passat, Golf, Jetta, etc.
Below are two pictures of an Eos (United Kingdom specification) that I took a couple of weeks ago when I was in the UK. The car has automatic light control, as evidenced by the light switch with the little 'tunnel' graphic on it. I didn't take a close-up picture of the rainsensor, but I am pretty sure it will be in one of the locations on either side of the mirror that are referenced by the arrows.
I will be back in Europe at the end of this week, I'll see if I can gather more information then.
Michael
*Eos with rain and lightsensor*
(location is presumed)

*Lightswitch from same vehicle*


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (PanEuropean)*

Michael,
Your assumption and your data is GREAT stuff, and I really appreciate it. I fear you are correct ... and thats a bummer because I sort of wanted to upgrade to the Auto light switch and add the coming home features. I'll be happy to suffice with a regular european light switch, but would love the auto feature.
But at time of purchase could not justify the $3,500+ pkg to add that (and a few other) features. Oh well... thanks for the info, as always!
Ari


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## PanEuropean (Nov 3, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

I visited my local VW dealer today, and had a look at the Eos that they keep in the showroom as a display item. It has a rain and light sensor installed. Below are pictures of the rain and light sensor, and also of the light switch. I suspect (am not sure, but strongly suspect) that the four little things in the middle - the brighter part - comprise the light sensor, and the blobs that are arranged in a circle around it comprise the rain sensor.
*NAR Eos*


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## Shaka (May 20, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (PanEuropean)*

Michael ... nobody can ever say you are not very thorough!


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## PanEuropean (Nov 3, 2001)

*Re: Do ALL Eos vehicles come with a light sensor? Where is it? (Shaka)*

Thanks, I try. 
My experience in the Phaeton forum over the past two years is that the forum works best (stays friendly, stays interesting) if the focus is kept on technical issues, and all of the forum members contribute lots of useful knowledge and facts. This keeps the focus away from personal issues, disagreements, etc., not to mention that it's a heck of a lot more interesting than reading someone's whine that the dealer didn't wash the car for them when they stopped by to get a burned out dome light replaced...








Michael


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