Brightness Setting NOT Holding

Question

Level 1

4 points

Brightness Setting NOT Holding

I have a rMBP and have brightness set to the highest setting when plugged in. The box to slightly dim the display when on battery power IS checked. The box "Automatically adjust brightness" is NOT checked. For some reason, the brightness setting is not holding properly.

For example, when I unplug the laptop, brightness does decrease as it should, however, that reduced brightness level is not always retained and brightness sometimes reduces further even though I haven't done anything to adjust brightness.

This seems to happen more when on battery power, i.e., when it is plugged in, it seems to hold the maximum brightness setting better.

I've now unchecked the box to slightly dim the display when on battery power to see if that changes things.

I've already done a clean install of Mountain Lion, but I still assume a program I'm running or something inherent in ML is causing this as I doubt this is a hardware issue.

Is anyone else experiencing this or does anyone have any thoughts?

MacBook Pro with Retina display, OS X Mountain Lion (10.8.1)

Posted on Sep 3, 2012 6:08 AM

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Answer 1

Shootist007

Level 6

16,703 points

Sep 3, 2012 6:33 AM in response to RMSko

Not in the OS. It is built into the firmware of the computer. If you boot the system and hold down the Option key the firmware one time Boot Menu screen will come up, No OS is Loaded only firmware boot option, and after a period of time the screenn will go dim then black out.

So it could be the OS or the firmware or both.

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Answer 2

RMSko Author

Level 1

4 points

Sep 3, 2012 7:15 AM in response to Shootist007

Thanks for the response. Any thoughts on how I could go about troubleshooting or fixing?

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Answer 3

Shootist007

Level 6

16,703 points

Sep 3, 2012 7:21 AM in response to RMSko

Could be your preference files are corrupted and even though you have unchecked the option to Auto adjust screen brightness it is still doing that.

The only way to fix that is to Delete that preference file, which is a Plist file, and reboot so it gets rebuilt. Which Plist file that is I have no idea.

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Answer 4

RMSko Author

Level 1

4 points

Sep 3, 2012 8:08 AM in response to Shootist007

Hmmm, the only reason I don't think it's the preference file is that the same thing was happening before I did the clean install of ML. Wouldn't a clean install of ML automatically rebuild that preference file?

I'm wondering whether this is my machine or whether it's something that is more widespread (that's probably wishful thinking though).

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Answer 5

RMSko Author

Level 1

4 points

Sep 3, 2012 8:39 AM in response to RMSko

I did see these other threads so there other people with the same issue as me (and probably more):

https://discussions.apple.com/thread/3825788?start=0&tstart=0

https://discussions.apple.com/thread/3550463?start=0&tstart=0

https://discussions.apple.com/thread/3482405?start=0&tstart=0

https://discussions.apple.com/thread/2614478?start=0&tstart=0

I'm also wondering whether it may make sense to reset the System Management Controller (SMC) - I guess it can't hurt?

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Answer 6

Shootist007

Level 6

16,703 points

Sep 3, 2012 8:52 AM in response to RMSko

Yes it would if you really did a clean install, everything would be new. As with a clean install you wipe/erase the drive before installing.

RMSko wrote:

Hmmm, the only reason I don't think it's the preference file is that the same thing was happening before I did the clean install of ML. Wouldn't a clean install of ML automatically rebuild that preference file?

I'm wondering whether this is my machine or whether it's something that is more widespread (that's probably wishful thinking though).

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Answer 7

RMSko Author

Level 1

4 points

Sep 3, 2012 9:07 AM in response to Shootist007

I actually don't think it's just my machine, especially since I found so many other threads with people having the same problem (links posted in reply above).

Do you know anything about the SMC? If yes, do you think it makes sense to try resetting this (I just don't want to screw something else up)?

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Answer 8

Shootist007

Level 6

16,703 points

Sep 3, 2012 9:18 AM in response to RMSko

SMC stands for System Management nController and would not screw anything up. It resets that to look at and record the hardware in your Mac along with resetting it to the default values.

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Answer 9

RMSko Author

Level 1

4 points

Sep 3, 2012 9:20 AM in response to Shootist007

Interesting. Do you think it could potentially address this issue?

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Answer 10

Shootist007

Level 6

16,703 points

Sep 3, 2012 9:27 AM in response to RMSko

Not sure but in any event it can't hurt it.

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