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iMac Pro iMac Pro Auto-Brightness

M

mzanker

macrumors 6502
Original poster
Jul 14, 2008
321
120
United Kingdom
Every few days auto-brightness stops working on my base model iMac Pro. It appears to happen when the display has been off for a while (I've disabled sleep when the display is off). It appears to get stuck in the dimmest setting.

Unchecking/checking the "Automatically adjust brightness" setting doesn't fix it - a restart is needed, which fixes it every time (until it happens again).

I'm hoping this is a software or firmware issue (or even a driver issue) and not a hardware fault. Anybody else had this happen?
 
I decided to start uninstalling hardware-related utilities to see if anything made a difference. The first thing I uninstalled was iStat Menus 6 and I haven't had the auto-brightness issue since.
 
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mzanker said:
Every few days auto-brightness stops working on my base model iMac Pro. It appears to happen when the display has been off for a while (I've disabled sleep when the display is off). It appears to get stuck in the dimmest setting.

Unchecking/checking the "Automatically adjust brightness" setting doesn't fix it - a restart is needed, which fixes it every time (until it happens again).

I'm hoping this is a software or firmware issue (or even a driver issue) and not a hardware fault. Anybody else had this happen?
Click to expand...
[doublepost=1522435768][/doublepost]My iMac PRO base model is dimming precisely as described above. I have no idea as to. what to do.
 
I think I'm experiencing something similar. I noticed after updating to 10.13.4 my screen brightness is set 2 bars away from max and needs to be manually readjusted after a restart/shutdown. I tried SMC/NVRAM resets, reinstalling High Sierra, deleting system preference and ambient plists, and nothing seems to work. Is anyone else experiencing this after updating or can anyone offer some suggestions to force screen brightness to lock and save?
 
boto said:
I think I'm experiencing something similar. I noticed after updating to 10.13.4 my screen brightness is set 2 bars away from max and needs to be manually readjusted after a restart/shutdown. I tried SMC/NVRAM resets, reinstalling High Sierra, deleting system preference and ambient plists, and nothing seems to work. Is anyone else experiencing this after updating or can anyone offer some suggestions to force screen brightness to lock and save?
Click to expand...
I have the same thing after the 10.13.4 update (iMac Pro 8c/Vega64/32gb). Apple's QC has really slipped the last year.
 
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Hmm I didn't realize the iMac Pro had this feature built-in, for my X-Rite Spectrometer I use for calibrating my monitors has that feature as well. Learn something new everyday.
 
Mac32 said:
I have the same thing after the 10.13.4 update (iMac Pro 8c/Vega64/32gb). Apple's QC has really slipped the last year.
Click to expand...

Every single MacOS update introduces more problems and things that slow me down. First they bricked Duet, now this, and who knows what will surface next.

At the end of the High Sierra cycle, no more OS updates for me until April/May of 2019. I have work to do and Apple’s lack of software QA is costing me money.
 
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boto said:
I think I'm experiencing something similar. I noticed after updating to 10.13.4 my screen brightness is set 2 bars away from max and needs to be manually readjusted after a restart/shutdown. I tried SMC/NVRAM resets, reinstalling High Sierra, deleting system preference and ambient plists, and nothing seems to work. Is anyone else experiencing this after updating or can anyone offer some suggestions to force screen brightness to lock and save?
Click to expand...

I have exactly the same issue. iMac Pro 8 core. Brightness resets to about 90 percent after each restart (2 bars from maximum.) Did PRAM reset and SMC reset (several times). No effect.
 
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EDS66 said:
I have exactly the same issue. iMac Pro 8 core. Brightness resets to about 90 percent after each restart (2 bars from maximum.) Did PRAM reset and SMC reset (several times). No effect.
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Identical problem.
 
mossback said:
Identical problem.
Click to expand...

This issue popped up on apple discussions forums yesterday as well:

https://discussions.apple.com/thread/8341298

I reported this to apple; hopefully others will as well. I don't think Apple bundled a firmware update for iMac Pro with 10.13.4. My guess is it's a kext issue. Unfortunately apple releases fixes at a tectonic pace, and we will probably have to live with this problem until the next High Sierra update.
 
Something else I noticed with brightness is when night shift is on and you adjust brightness up to the second to last bar and then advance to last bar there is no change in the brightness. When night shift is off the brightness adjustment works correctly, adjust from second to last bar to full brightness and you can see the screen get brighter. Very strange. By the way the auto brightness on my IMac Pro behaves differently than what is being described in this post. Mine adjusts to almost full brightness when there is bright sunlight in the office, however as the sun goes down my screen brightness drops down to 3-4 bars which is too dim. When I turn on bright lights in the office the brightness might go up 2 bars at the most. I am running 10.13.4. Apple needs to spend a lot more time doing testing before releasing these updates especially with these flagship models.
 
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I don't think there is much you can do, other than reporting this to Apple. One of the contributors in the apple support forums I referenced above reported that Apple Engineering is looking at it and that he has another call scheduled on Thursday. Hopefully, if enough iMac Pro owners report this problem, Apple will release a fix in short order. But given their track record, we will probably have to wait until the next High Sierra update.
 
I disabled "Adjust keyboard brightness in low light" under the "Keyboard" Panel under "System Preferences" and the screen dimming seems to be fixed. Perhaps this control gets sent to the display screen instead of the keyboard.
 
daveives said:
I disabled "Adjust keyboard brightness in low light" under the "Keyboard" Panel under "System Preferences" and the screen dimming seems to be fixed. Perhaps this control gets sent to the display screen instead of the keyboard.
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Which keyboard are you using? I don't appear to have that option (using space grey bluetooth keyboard).
 
daveives said:
I disabled "Adjust keyboard brightness in low light" under the "Keyboard" Panel under "System Preferences" and the screen dimming seems to be fixed. Perhaps this control gets sent to the display screen instead of the keyboard.
Click to expand...
system 10.13.3 1 month old space grey (like black silicone)
 
So, I reverted to 10.13.3 (from recovery) and the iMac Pro still does not remember the brightness level on restart. Must be a firmware issue.
 
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firmware got updated with 10.3.4 so it's possible. Did you try to reset SMC/NVRAM ?
 
Apparently this problem predates 10.13.4, at least according to the support call one of the members of Apple Support forums had with Apple Support. I reverted to 10.13.3 and the issue persists. It's quite possible I simply never noticed it before.
 
In my case, the issue was not present in 10.3.4

Perhaps reverting does not alter the parameters in question?
 
mossback said:
In my case, the issue was not present in 10.3.4

Perhaps reverting does not alter the parameters in question?
Click to expand...

If the firmware update did it, then reverting to a pre 10.13.4 build would definitely not help things. SMC and PRAM resets are not effective, by the way. I've tried both several times after downgrading to 10.13.3.

The problem does not bother me too much, as I rarely restart the computer and never use automatic brightness adjustment -- don't really see much utility in it.

Let's hold our fingers crossed and hope Apple releases a fix -- either software or firmware -- without too much procrastination.
 
My apologies! I meant to say 10.3.3 in the above post.

To clarify, I'm running 10.3.4 currently and the issue is present. But it was not with 10.3.3
 
EDS66 said:
If the firmware update did it, then reverting to a pre 10.13.4 build would definitely not help things. SMC and PRAM resets are not effective, by the way. I've tried both several times after downgrading to 10.13.3.

The problem does not bother me too much, as I rarely restart the computer and never use automatic brightness adjustment -- don't really see much utility in it.

Let's hold our fingers crossed and hope Apple releases a fix -- either software or firmware -- without too much procrastination.
Click to expand...
mossback said:
My apologies! I meant to say 10.3.3 in the above post.

To clarify, I'm running 10.3.4 currently and the issue is present. But it was not with 10.3.3
Click to expand...

You mean 10.13.3
 
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