I have an Inspiron 13 7368 that I bought a couple years ago. Recently, after a bunch of updates (including Windows updates, BIOS update, and driver updates), the screen started to dim after a seemingly random amount of time. I normally keep the brightness at 30, but when the screen dims, it's so dark that even at 100 brightness, it's still too dark.
I've tried every setting I can find, including BIOS (1.17.0) video settings. The only thing that seems to help is rebooting, and that only temporarily resets the brightness until the screen randomly dims again.
Thank you for your message here.
Please boot into BIOS and check if the issue persists - if it does, it would be a hardware issue.
Please update BIOS to the latest version 1.18.0 ,1.18.0 from our support site to check if this resolves it - https://dell.to/2V72BtI
Thanks for updating the BIOS on the computer. Please boot into BIOS (F2 during startup) and check if the screen dims - if it does, please share a video of it.
For my reference, please click on the message tab next to your avatar– click “New Message” & search for my Dell username (DCFAdmin) & send a private message with the service tag, registered name & email address.
Rebooting the laptop resets the screen brightness. The issue seems to occur randomly, sometimes taking hours. I'm not able to consistently repro it in Windows. I don't know if I would be able to repro it in BIOS, let alone catch it on video.
I'm having the same issue with my Inspiron 15 3567 laptop.
It started after the last Windows 10 update. For no known reason, the screen will suddenly dim (plugged in to AC) and then go back to normal. It's very random. It happens daily though, just no known way to recreate it and no pattern (like specific website etc). I'll be looking at a webpage and it will just dim, stay dim for differing amounts of time but no more than 5 seconds, then go back to normal. I have run the Support Assist and updated the Bios but it still continues. I have restarted the laptop several times, cleared cache and even wiggled the power cord in case that's it. I can't figure out what is causing it.