iPhone screen dims randomly

I have been having this issue also. I have noticed it more while testing an app that is currently under development. It seems to happen when the phone has been under a considerable load. While debugging - I can see the energy usage of the app is very high. After some time the phone begins to heat up. While looking into this, I found another thread that said it was because of heat. I am tending to think this is probably right. After the phone cools off it seems to go back to normal.

REASON:

If a phone gets too hot then it will automatically lowers brightness to help cool it down. If brightness is lowered but still gets hot from processing then it will drop brightness even more making it very dim. This happens a lot when I play a high graphics games like PUBG. Once the device drops back down to certain temperature then brightness goes back to normal.

MY SOLUTION:

I remove the case when playing games that have high demanding graphics and this allows phone to not overheat or cool down much quicker. Most phone cases create an "insulation layer" around phone trapping heat from the processor inside causing it to overheat.

https://support.apple.com/en-us/HT201678

No, I know! My magnifier is, and was, off...but if you click on magnifier anyway, there is an Auto-Brightness setting which was set to on for me. I turned that Auto-Brightness off, and (even though the magnifier was still off) the problem went away. (shrug) Makes no sense, I know.

That happens if you have an app that’s using a lot of power to complete a task in the background, please go to settings>battery> And scroll down to the graph that shows the battery usage, it will tell you what app is taking up the battery and then tell you what the app is doing in the background by clicking show activity.

Hi.

I had the same problem.

Try the following: turn off Reduce White Point by

Settings>General>Accessibility>Display Accomodations>Reduce White Point

Worked for me.

For those who have not tried it yet

Settings > Face ID & Passcode > enter passcode > scroll down to Attention Aware Features and switch OFF

Panchososa694 I have to apoligize and eat crow... when you posted your original response regarding Attention Aware I confused it with something else. I went back through this thread and when I read your suggestion about checking Attention Aware settings I realized that I actually had NOT turned it off and neither had the genius’ at the Apple Store or was it suggested by the representatives I spoke to over the phone at Apple. As soon as I read what Attention Aware does, it totally made sense. Let’s see if this does the trick 🏼

Now I’m not too sure it is a heat issue. I was driving today, using Waze and like clockwork the screen dimmed. I quit Waze and after a few minutes the screen was back to normal. I used Waze again and after like 2 minutes screen dims.

So I launched Apple Maps and no screen dimming. I had Apple Maps running for maybe 10 minutes all good. I switch to Waze and within 2 minutes screen dimmed.

At least for me it’s only when I run Waze. Now it could be iOS 11 feels Waze is making the phone hot and dims the screen to protect it?

Another thing I found was my wife who has an iPhone 6, her screen will do the same but she is using Safari to read books. She too is running iOS 11.2.6

So maybe it’s a bug in iOS thinking the phone is getting hot when in reality it isn’t?

Did you by chance try one of the now obvious first steps and turn off Auto Brightness in Display Accommodations as well as turn off reduce white point in that same menu.

Also try disabling the Require Attention for Face ID and the Attention Aware Features which play active roles in dimming.

See if that helps. I am not having the dimming issues with my iPhone X any longer and i have several settings disable. However it will dim slightly if on my dash with Waze on a sunny warm day, and the phone starts to get pretty hot, but I just push the air conditioning up to the font window and it brightens a few minutes later.

Hope this helps a little.

After checking this with Apple, it appeared to be a feature, not a bug, to prevent Burn-in when the phone is hot because the iPhone X has an OLED screen which will burn-in if it is too bright and hot. So the phone dims the display to prevent burn-in.

I just have to say I had the problem with random dimming multiple times a day, I had tried every suggestion in these fifteen pages, and then I read Joanna's post about the second auto-brightness setting. That was a new one on me, so I went to settings to see for myself, and there it was. My magnifier was turned off, but I switched the second auto-brightness off anyway, muttering that this was just another waste of time—if the magnifier's off to begin with it's ridiculous to think changing a setting for it is going to make any difference.

I said that then, but today I say danged if four days later I haven't seen the dimming problem once.

So at risk of jinxing it, cheers to you, Joanna. 🍸 Makes no sense to me that that setting could matter, but I can't argue with results.

Sergio, chill the freak out with your posting the same thing 93 times.

https://support.apple.com/en-us/HT201252

Do that and set up the phone as new, NOT from a backup. If it continues, make a genius bar appointment.

If that happened to me and you're sure all brightness settings are correct, I would reset the iPhone as follows:

• Briefly press and release the volume up button.
• Briefly press and release the volume down button.
• Press and hold the side button until the Apple logo appears.

If that does not solve it, visit an Apple Store or Authorized Apple Service Center. Your iPhone is warrantied if this is caused by some manufacturing issue.

Happened to me today on iPhone 7. Using Apple Maps with phone on dash in a holder. After about 10 minutes of driving (with sun on back of phone I might add), the screened dimmed to the point I could barely see the map info. It stayed that way for the rest of the trip (over an hour). Closed Maps, put the phone in my pocket and did my shopping. Placed the phone in its holder and started back home. Screen was full brightness. Again, 10-15 minutes later (with sun still on back of the phone), the phone dimmed to previous low level even though Brightness Level was at 100%.

The phone is space grey and does gets pretty darn hot when using Maps and with sun on it. So it seems that cooled down, the brightness returns. Definitely seems like a heat issue.

All software is current and battery was fully charged.

Check the attention aware features

https://support.apple.com/en-us/HT208245