Brightness function keys +/- cannot increase the brightness on display. Other function keys are working properly.
The issue is highly related to a Windows update which upgraded the graphic video driver to version 10.18.10.3958 released 2014/09/30 or 10.18.10.4276 released on 2015/8/17. These versions are known to cause loss of brightness control. Restoring the previous driver should also restore brightness control.
The above symptom may occur to the following systems:
IdeaPad Z500, Z400
The above symptom may occur under the following operating system:
Microsoft Windows 7, Windows 8.1
- Go to Device Manager (how to enter Device Manager)
- Select Display adapters and scroll down
- Right click on Inter(R) HD Graphics4000 and select Properties option
- Go to tab Drivers in the pop up window
- Push the Rollback Driver button (If Rollback Driver is greyed out which means no earlier versions were installed)
- Wait until it is done. Your system should recover the brightness and the increase/decrease functions in the keyboard.
- If the previous step does not resolve the issue, please upgrade Intel Video Driver to the latest.
- Windows 7 Intel Video Driver: Download here
- Windows 8.1 Intel Video Driver: Download here
- Check to see if brightness controls have been restored using the brightness keys.
As Z500 and Z400 are not Windows 10 supported hence you're not advised to upgrade to Windows 10. Should you insist to install Windows 10 and have this brightness issue, please check out this forum peer-to-peer discussion.