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daylight sensor: how to make it more sensitive?

19K views 61 replies 23 participants last post by  *Ed8r* 
#1 · (Edited)
My question is, how does the sensor work? Does it detect angle of rays or overall brightness or what?

I do most of my driving between Salinas and Monterey, CA, so that means lots of marine-layer days, with low lying cloud cover or high fog, however you want to picture it. These gray, dark days need headlights for safe driving, but my daylight sensor seems to think there's enough light that headlights are not needed.

What can I do* ... short of taping it over completely dark with a swath of duct tape ... to encourage the headlights to turn on, on these gray days?

Anyone have useful ideas?


*Yes, I know I can just manually turn the headlights on and off, but I'm trying to find a workaround.

[EDIT: I should have titled/asked about how to make it LESS sensitive!]
 
#2 ·
I agree, the auto headlights suck. It gets way too dark before they turn on. The easiest thing is probably to find something semi-transparent and stick it over the sensor, like you said. The translucent Scotch tape might work, or a bit of window tint... Let us know if you find something good.
 
#3 ·
square post-its?

Currently I have the sensor covered with 2" x 2" Post-it notes.

A single layer was definitely not enough, so now I have a double layer of pink post-its and they happen to be sort of tweaked so they lie almost cupped around it, even though they are only stuck at the very front. It helps, but isn't quite enough yet.

I'm afraid to try anything more permanent ... I read somewhere a suggestion of marking it up with a black permanent marker! ... but I'm not prepared to try that yet.

There are enough people who are frustrated with it that I don't understand why the engineers haven't found a workable solution yet!
 
#4 ·
Currently I have the sensor covered with 2" x 2" Post-it notes.

A single layer was definitely not enough, so now I have a double layer of pink post-its and they happen to be sort of tweaked so they lie almost cupped around it, even though they are only stuck at the very front. It helps, but isn't quite enough yet.

I'm afraid to try anything more permanent ... I read somewhere a suggestion of marking it up with a black permanent marker! ... but I'm not prepared to try that yet.

There are enough people who are frustrated with it that I don't understand why the engineers haven't found a workable solution yet!
Sorry maybe I haven't read up on this enough, but when I find the lights should be on but aren't, I just turn them on. If I forget when I get out of the car it beeps. It's really a minor annoyance, unless maybe you guys are talking about them not coming on at all...?
 
#5 ·
More like the opposite. We want them to come on automatically "sooner," i.e., before it gets even darker.

Yes, of course we can turn them on and off manually (as mentioned in my OP), but we're looking for something to make them do it automatically.
 
#8 ·
Tell me about it. I have to kneel sideways on the driver's seat, brace myself with one hand on the passenger seat, and then reach to the full extent in the opposite direction. What were they thinking?

I think I can do that to get a piece of black electrical tape up there, but a sharpie marker? Not so much (even though I'd rather try this, using removable tape . . . the tacky kind that doesn't leave any residue).
 
#11 ·
My question is, how does the sensor work? Does it detect angle of rays or overall brightness or what?
The light sensor, mounted on the center of the dash facing forward, works off overall brightness. The Body Control Module sends a 5 volt signal to the light sensor and the sensor provides a variable ground resistance to that signal based on ambient light level, with less resistance to ground at lighter ambient conditions.

Short of getting into the wiring in the dash and adding a resistor in the ground side of the circuit, about all you can do is try to 'spoof' the sensor into thinking it's darker than it is. The most innovative solution I've seen so far was the Titanium I saw a few months ago where they had placed a lens from a pair of (broken) sunglasses over the sensor.

It would be great if we were able to vary the sensitivity of the light sensor in the message center, as not everyone wants the same settings.
 
#12 ·
Great idea about the sunglasses lens! And I just happen to have a pair that are scratched and ready to be disposed of, so I'll try it and report back . . .

Thanks!


* Oh, and many thanks also for giving me a basic idea of how it functions. I was thinking that knowing the principle might help me think of a way to "spoof" it, but you provided that thought as well!
 
#15 · (Edited)
You're welcome.

I just wish I'd taken a picture of the car that I saw with the lens on it or had looked a little harder to try to figure out how they kept it from sliding around in a turn. There was nothing obvious, so maybe they used double-backed tape or something.

Please let us know how it works out for you.

EDIT: It should be noted that on vehicles equipped with the Dual Automatic Temperature Control (DATC) system, the light sensor also serves as a 'sunload' sensor for the airconditioning system and supplies information to the HVAC module proportional to the intensity of the sun on the vehicle.

If you're 'spoofing' the light sensor, it may also result in the cabin temp being a bit warmer (or at least slower to cool to set temp) on sunny days.
 
#14 ·
Mine come in when it's just getting dark. Then again I didn't see the point in having my headlights on before yet I could see.. But people would high beam on account that I didn't have them on. Iuno, perhaps my eyes function better then others? Lol

Sent from Samsung Galaxy S2 using Tapatalk 2. [Android build 4.0.4]
 
#17 ·
Mine come in when it's just getting dark. Then again I didn't see the point in having my headlights on before yet I could see.. But people would high beam on account that I didn't have them on. Iuno, perhaps my eyes function better then others? Lol

Sent from Samsung Galaxy S2 using FF Mobile 2. [Android build 4.0.4]
You do know that headlights aren't just so you can see, but also so people can see you, right? If not, [insert your God here] save us all!

I agree I'd like to see them come on sooner. I might try the tint thing, but that's a tight area to work in.

Posted via FF Mobile
 
#20 ·
I've never been in an accident.. Why get upset about someone else's views?.. I see black cars just the same as red and yellow. Easily. They all have reflectors here in Canada. ;-)

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#24 ·
This is probably getting OT, but . . .

I see black cars just the same as red and yellow. Easily.
Yes, but black is not the problem, necessarily. I don't remember (I suppose I could Google, but I'm lazy) from color studies which colors "disappear" first in low-level light, but some (maybe grays? or gray-greens?) tend to fade into the background sooner than others.
 
#22 ·
someone mentioned the sun glasses; could you slip a small piece of tint on the windshield over the lens? tint will stick and you can get a huge range of %'s.
 
#23 ·
Not sure that would work being the rays hit it from all sorts of angles. Legally as well (in NY) you can't have tint on the windshield anywhere below 6 inches from the top. Yes they'd probably give you a ticket for it here.
 
#26 ·
I guess instead of tinting a small section above the sensor, the tint would stick to the sensor as well. It would be more temporary than the sharpie idea that was thrown out.

but....every time I think about this, I think, "how hard is it to flip the switch?" you are thinking about the lights anyway so its not like it is really auto anyway.
 
#28 ·
I had mentioned tinting the sensor itself previously, but it's such a tight spot it would be tough to do...at least to have it look good. And I agree with you. Anytime I feel my headlights should be on and they're not, I flip the switch.
 
#30 ·
This is my first car that has the dash lights on all the time. I was not used to looking for the little green headlamp on the bottom of the tach to know if my lights were on or not. That is why I put the 3/8 square of black tape centered on the sensor. It works exactly when I would turn the lights on or off myself. It is also unobtrusive.
 
#31 ·
I had the perfect marine-layer day to try out timthom62's sunglasses lens idea today. One lens did not work; I might try a doubled lens tomorrow. But I'm definitely keeping the electrical tape idea in the back of my mind . . . thank you, brent!

And you people who find this discussion ridiculous [I'm looking at you, FrostedG] can just go on your merry way turning the lights on and off manually while the rest of us try to figure this out.
 
#38 ·
I placed a lightdim dot on the top of the sensor and it's working great. Easy to place and they peel off clean. I used an xacto knife to carefully place the dot, it made it pretty easy to get into such a tight spot. It's also helpful to have someone guide the placement from outside the car. http://lightdims.com/
Thanks for the great idea!

I look forward to trying these on the sensor of my autodimming rearview mirror, which never has been as dark as I'd like.
 
#36 ·
I used the original (50%-80%), sorry I didn't mention that. I purchased these a year or two ago when the original was the only offering. The sheet includes a variety of sizes and shapes. I used the 3/4" dot.

This appears to happen on the Manual Temperature Control system too... When the sensor is shaded, A/C output is reduced... Probably to increase fuel mileage..

As far as certain colors of cars becoming harder to see as it gets dark, I notice my silver car at dusk or dawn becomes almost invisible once you get about 30 yards or so from it... especially if theres a little dew in the air..
I hadn't even considered the impact on temp control. I'll have to see if I notice a difference. The nice thing about this mod is it's so easy to undo.
 
#39 ·
To be clear, I don't mind manually turning the headlights off and on. The trouble I have is that the dash is lit regardless of whether the headlights are on or off. On older cars, in rainy and/or overcast situations, you were sort of "prompted" to turn on the lights because it got hard to read your speedometer with no backlighting. If you forget to set your lights to Auto because you were using them manually, it's easy to find yourself driving in a semi-dark situation with your headlights on because you can read the dash just fine even with the lights off.

Don't get me wrong, this isn't an end-of-the-world situation, but yeah a "nice to have" feature would be adjustable auto headlights, or at least a sensor that turned them on earlier.
 
#40 ·
I'm back to offer this update:

We've finally had another day with the right kind of overcast for me to try out my new lightdim dot. I'm disappointed to find that the 3/4 dot is definitely not enough.

Over my lunch, I peeled off the dot and cut a slightly elongated square from the 25mm X 57mm strip. I applied this across the sensor, front to back (probably makes no difference). This piece didn't do it either.

Next, I think I'll double up the 25mm strip, but running side to side.

I'll come back here to check in and record results!
 
#41 ·
Here I am again.

Doubled the 25mm strip, but now the lights are on even when it's bright enough to trigger some tint in my transition lenses. I'm going to scrape the whole thing off and start again by adding a dot and then one layer of the 25 mm strip.

I'll be seeing ya!
 
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