How to make the ambient light sensing work?

[programmer<3]

I have a 1 week old macbook pro 15" mid-2014. The ambient light sensing doesn't seem to work. Even when I cover the facetime camera with a black cloth, the keyboard backlight doesn't come on. What should I do?

Thank you.

 

[Bruno09]

Hi,

in System Preferences / Keyboard / Keyboard tab, check the "Illuminate in low light conditions" box.

Also check that the keyboard backlight is not turned off : F5/F6 keys (or other, as it actually depends on the model)

 

[joe-h2o]

Does it come on in a dark room, and does the display dim when you cover the sensor?

Cupping your hand over it should be enough to see if the system is responding to ambient conditions. Also check to see if the box is checked in display preferences.

The keyboard lights up when it's properly dim in the room - if it's still quite bright and you're trying to fake it out, then it might still be too bright, or you might not be able to see the keys illuminated - it's quite a subtle effect.

 

[programmer<3]

Does it come on in a dark room, and does the display dim when you cover the sensor?

Cupping your hand over it should be enough to see if the system is responding to ambient conditions. Also check to see if the box is checked in display preferences.

The keyboard lights up when it's properly dim in the room - if it's still quite bright and you're trying to fake it out, then it might still be too bright, or you might not be able to see the keys illuminated - it's quite a subtle effect.

I checked my system preferences. Automatic adjustments are on. Also, I took my mac to a dimly-lit room and placed the black cleaning cloth on the facetime camera to ensure no light could reach the sensor. The keyboard backlight didn't come on. I did an SMC and NVRAM reset. No difference. What to do?

 

[Bruno09]

Check that you did not turn the backlight off manually.

Try to turn it on with the right key.

http://geauxapple.com/2011/11/apple-portables-key-placement-and-functions/

Source : http://support.apple.com/kb/HT3164

 

[programmer<3]

My keyboard brightness is set to 1 unit. Ok, so after a bit of testing, this is what is happening:

When I place a black cloth on the facetime camera, the brightness of keyboard backlight doesn't increase.

When I manually set the keyboard backlight to the highest and then put led light on my facetime camera, the keyboard backlight goes off and the screen becomes very bright.

Is this the expected behaviour. I think the sensors are fine. But is the behaviour fine?

How does ALS work on your laptops?

 

[Bruno09]

When I place a black cloth on the facetime camera, the brightness of keyboard backlight doesn't increase.

Yes, of course : when you are in the darkness, the keyboard backlight must decrease (not increase).

Since you manually put it to 1, it can't go lower....

When you put a led light on your facetime camera, it's like you were it a very bright area ---> you no longer need a backlit keyboard, so the backlight turns off.

As for the screen, see System Preferences / Displays.

 

[programmer<3]

Yes, of course : when you are in the darkness, the keyboard backlight must decrease (not increase).

Since you manually put it to 1, it can't go lower....

When you put a led light on your facetime camera, it's like you were it a very bright area ---> you no longer need a backlit keyboard, so the backlight turns off.

As for the screen, see System Preferences / Displays.

But when my backlight is off, and I go to a dark room, it doesn't come on....

Also, are SMC and NVRAM reset safe for a macbook? Should these be done on regular basis?

 

[Bruno09]

But when my backlight is off, and I go to a dark room, it doesn't come on....

If it's off because you switched it off manually, it's off and won't come on in a dark room.

Also, are SMC and NVRAM reset safe for a macbook? Should these be done on regular basis?

It's safe, and does not need to be done on a regular basis.
Only to solve some specific issues.