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Imac Desktop, 21-in Intel (late 2019)
Lost brightness control. Can fully dim, but only increase to about 50%. Prior to loss of control display flicked a bit.
Tried NVRAM and SMC reset without success. Apple diagnostics returned ADP000, no hardware issues.
Don't know what steps to try next.
iMac (2017 – 2020)
It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.
When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.
For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.
None of the usual suspects show up in your report so please do the following:
The following will require any USB keyboard and mouse. If you don’t have them, borrow or buy them, they are inexpensive!
1. Connect the USB keyboard and mouse to the computer.
2. Open System Preferences – Bluetooth
3. Un-pair the wireless keyboard and mouse.
4. Turn off Bluetooth
5. Restart the computer in Safe Mode per the directions in Use safe mode on your Mac - Apple Support
6. Restart the computer normally.
7. Open System Preferences – Bluetooth
8. Turn on Bluetooth
9. Re-Pair the wireless keyboard and mouse.
10. Unplug the USB keyboard and mouse and begin testing the wireless devices again.
If that does not work, then your keyboard may have failed and needs to be replaced.
Restart in Safe Mode. If those do not work, try another keyboard.
I already gave you another suggestion, try another keyboard.
By the way, do you have any of the following apps installed? Please answer, it's critical.
Tried Safe Mode, but display brightness issue remained. Keyboard is blue tooth and F1 and F2 functions appear to function correctly. Can decrease brightness to zero, but increase is only to about the 25% mark.
Any other suggestions? Going crazy.
Okay, please uninstall the VPN app per the developers instructions and then restart again in Safe Mode. Make sure the wireless keyboard is plugged in to the computer so it is acting as a wired keyboard.
Completed the VPN app uninstall and Safe restart. I also logged in as a different user. Still having problems with brightness control.
Moving the control slider to the left causes the screen to start to darken at the second marker (of 16 markers). Moving the slider to the right returns the brightness also at the second marker. The brightness level remains the same through to the 100% mark.
Thanks for all the help, I'll obtain a wired keyboard in the next few days.
Just for clarification, both the wireless keyboard and mouse do move the brightness sliders. So, despite the sliders moving on screen, there can still be no actual functionality-correct?
VPN app installed, not in use but can easily remove.
Don't have another keyboard…anyway test without another piece of hardware?
Lost Brightness Control
