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Discussion Starter #1
It appears that the instrument lighting in my car adjusts its daytime backlighting...but not always properly. Does anyone know where the ambient light sensor is? Is there any way to change the responsiveness to this sensor?

thx,

Dan
 

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Now the instrument lighting is a bit strange. The instrument sectors and numbers aren't clearly marked they are dark. Some days you get in and they aren't clear so I put the lights on Auto and the lights come on and sometimes they don't you have to turn the lights all the way on. Sometimes you can the driving and the instrument lights come on on their own.

Obviously you have the seperate rotary instrument illumination switch which I always set on full. As regards where the light sensor is I would assume its behind the interior mirror where the rain sensor is.

Whether there is a setting in VCDS to adjust the sensitivity I haven't looked.
 

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How many times have you been driving at night, dusk, dawn or heavy rain and suddenly come up on a car whose taillights are not on? Some scary stuff, sometimes.

Often it is because the driver didn't turn on his/her lights because a) the dash is backlit and b) they see their DRLs.

The variable backlighting on the dash is not there to adjust to lighting. It dims to remind you to turn on your main headlights in low light conditions.

The sensor is in the tach, lower right quadrant. I don't know if it is adjustable, but the point is it makes you consider lighting and whether to turn on your mains. You'll probably get used to it.

It's actually a thoughtful feature.

P.
 

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How many times have you been driving at night, dusk, dawn or heavy rain and suddenly come up on a car whose taillights are not on? Some scary stuff, sometimes.

Often it is because the driver didn't turn on his/her lights because a) the dash is backlit and b) they see their DRLs.

The variable backlighting on the dash is not there to adjust to lighting. It dims to remind you to turn on your main headlights in low light conditions.

The sensor is in the tach, lower right quadrant. I don't know if it is adjustable, but the point is it makes you consider lighting and whether to turn on your mains. You'll probably get used to it.

It's actually a thoughtful feature.

P.
That's right the above post is correct...its a safety feature, and a good one i might add. If your display is dim and tough to see that means you should have your lights on. The sensitivity is not adjustable, but there are settings in VCDS in the instruments module that allow you to choose whether you want the needles to remain bright or not and whether you want the MFD to remain bright or not. There may be another selection or two that I've forgotten about but you can check it out. I'll see if I can go back look myself and post the screenshots.
 

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No its not a good safety feature as Paul has said. You could be driving at dusk and the instrument lights come on and you assume the main lights are on when they aren't.
 

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You could be driving at dusk and the instrument lights come on and you assume the main lights are on when they aren't.
You may be missing his point. The instrument panel lights will not illuminate in the situation you describe. The instrument panel lights are designed to remain unlighted in low light situations to suggest that you turn your lights on. Not to mention the "DRL" indicator in the tach will advise you that your main lights are not on.

IIRC, the sensor is located between the 5 and 6 in the tach.
 

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No its not a good safety feature as Paul has said. You could be driving at dusk and the instrument lights come on and you assume the main lights are on when they aren't.
As others have said, I find it to be a great safety feature. Your UK model might be set up a bit differently, but I noticed this unusual approach to instrument lighting the first few days I had my car.

In broad daylight, with the headlights OFF, the instruments light up nice and bright for readability.

Drive into a low-light area, and the instrument lights dim so that they become hard to read, and the driver is prompted to switch ON the headlights to restore full instrument lighting. The sensor is sensitive enough that even the tree canopy on my block produces enough shade to dim the instrument lights during the day. By the time dusk comes around, it's dim enough outside that the instruments are also dim, and I am reminded to turn on my headlights. To see this in action, drive into a parking garage or under a large viaduct and watch the instrument lights dim completely over a few seconds, leaving only the needles glowing.

The advantage of this system is crisp, bright instrument lighting in the daytime without the risk of forgetting to turn on your headlights. I see this all the time; people driving around the well-lit streets and highways of Chicago with no visual cues that their headlights are OFF because their instruments are still brightly lit.

One thing, though: if the sensor hardware is there (and it seems to accurately judge light conditions), why not just have automatic headlights as well? Despite the usefulness of the system, it seems like a pretty complicated way to simply remind the driver to turn the headlights on.
 

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Keith, I'm not sure where you're coming from on this one...the whole point of the light sensitive gauges is that as it gets dark out the gauges will dim out so that you can't see them, this will prompt you to say..."hmm why can't I see my gauges", and then think "oh, my lights must be off". It is absolutely a great feature, and it works very well. I've never had the instrument lights come on when the exterior lights are off when it is not daytime. The gauges need a certain amount of ambient day light to be backlit and even the interior lights in the car at night are not enough to do that. The nature of this type of circuit suggests it is designed to fail (heaven forbid) such that it would fail with no backlighting of the gauges...at that point if you wanted to see the gauges you'd just turn the headlights on all the time until you get it fixed.

Also, we've discussed in other threads abt the US models (at least) having a DRL indicator on the dash. This is helpful too because if its getting dark out, I see that green DRL glowing in my lower right of my speedo (if the dimming gauges weren't enough of a clue) and will switch my headlights on. Note that the only (for lack of a better term) "flaw" in the system is that if you put your parking lights on ("euroswitch" equipped models), the gauges will remain lit and your parking lights will be on and it could get dark enough to require headlights and you would have no interior warning unless you are on a dark road, but at least the parking/marker lights give you some outboard visibility to other vehicles.
 

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One thing, though: if the sensor hardware is there (and it seems to accurately judge light conditions), why not just have automatic headlights as well? Despite the usefulness of the system, it seems like a pretty complicated way to simply remind the driver to turn the headlights on.
I agree with you wholeheartedly and have wondered this myself since I've had the car. I figured the issue could be that for compliance purposes the measure of ambient light to activate the headlights probably needs to come from a place in the vehicle that gets direct outdoor light...but in that case, they could have just put one sensor in that position instead of the one on the tach and then another behind the mirror for vehicles with the auto headlights.
 

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Discussion Starter #10
Goodness gracious...so many responses. The reason I asked the question is that the daytime backlighting seems inconsistent. Sometimes it's well lit and other times it's dark. Given the inconsistent behavior, I don't think this is intentional. Seems to me that the algorithm that controls this needs to be re-written.

What I've garnered from the various responses is that the belief is that the sensor is on the tach face and that nobody knows how to adjust sensitivity.

thanks all,

Dan
 

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Goodness gracious...so many responses. The reason I asked the question is that the daytime backlighting seems inconsistent. Sometimes it's well lit and other times it's dark. Given the inconsistent behavior, I don't think this is intentional. Seems to me that the algorithm that controls this needs to be re-written.
It is intentional. The algorithm is correct if you consider what it is trying to do. When lighting is bright, your dash has backlights on to make it clear and readable. When lighting is dim, your dash lights dim in order to remind you to turn you lights on. It is consistent, but can go dim in shadow conditions. Still, the choice is yours whether you turn your lights on or not, the dimming of dash lights is just a reminder/warning.

What I've garnered from the various responses is that the belief is that the sensor is on the tach face and that nobody knows how to adjust sensitivity.
The sensor is on the tach face, it is not a belief. The sensitivity cannot be adjusted to your liking because the lights work the opposite way from what you think you want.

thanks all,

Dan
You're welcome.

P.
 

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Discussion Starter #12
It is intentional. The algorithm is correct if you consider what it is trying to do. When lighting is bright, your dash has backlights on to make it clear and readable. When lighting is dim, your dash lights dim in order to remind you to turn you lights on. It is consistent, but can go dim in shadow conditions. Still, the choice is yours whether you turn your lights on or not, the dimming of dash lights is just a reminder/warning.



The sensor is on the tach face, it is not a belief. The sensitivity cannot be adjusted to your liking because the lights work the opposite way from what you think you want.



You're welcome.

P.
Thanks for sharing your opinions on this matter.

Dan
 
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