iPhone Screen Dims to 50% Randomly

[Ponta]

It happened on my iPhone 6, and now it's happening on my iPhone 8 Plus. I will be in bright, broad daylight, and suddenly the display dims so I can hardly see it. I go to the Brightness controls, and they only change the brightness from 0% ~ 50%; from the halfway point upwards, there is no change in brightness.

I have tried everything short of a wipe and reinstall. I have set all the the usual suspects—No True Tone, no Night Shift, no Zoom, no Color Filters, Invert Colors, Auto Brightness, or White Point. It's all turned off. And yet the danged thing still goes dark, stays that way for several minutes, then brightens up—never with any external input.

I do put black electrical tape over the front-facing camera. However, I don't see how a permanent light block could cause erratic light changes.

Any ideas what's up? Any suggestions? Thanks!

 

[Minho]

Try removing the tape for a few days to see if that solves the problem. Two different phones, same problem, common denominator is black tape over the ALS (ambient light sensor).

 

[Ponta]

OK, maybe I had it wrong—I though the ambient light sensor was the same opening as the proximity sensor—which I do not cover. Are you saying that it is now housed in the camera?

 

[Minho]

OK, maybe I had it wrong—I though the ambient light sensor was the same opening as the proximity sensor—which I do not cover. Are you saying that it is now housed in the camera?

Never mind, I just looked at an iPhone 8 Plus screen in more detail and the ALS is not close to the camera at all, at least not from the perspective of covering the camera with tape. It is much closer on the iPhone 6 and depending on how you cutout the tape, that could be impacting the ALS.

Considering the iPhone 8 is brand new, I would go the Apple store to have them take a look at it.

 

[Ponta]

I tried removing the tape. No change. The screen still dims.

Maddeningly, it usually dims in bright, broad daylight, and never at night (when I want it to). WTH?