My Lenovo Thinkpad X201 automatically changes display brightness from time to time. The specs do not mention an ambient light sensor. Power management settings are on Presentation (timers off). Any ideas on how to turn this behavior off?
I had this too. Unfortunately I don't remember exactly how I fixed it, but I think it went away when I disabled most of the junk Lenovo puts in the Windows startup folders. Install CCleaner, go to Tools/Startup and try disabling stuff. It's perfectly safe, if anything goes wrong just re-enable it.
Please let us know if you find the exact process, because this is something I'd like to switch on manually when out in the sunlight. But the auto sensor was way too sensitive.
You need to disable your graphics chipsets Adaptive Brightness (Intel) or Vari-Bright (AMD) option.
On my x120e I had to:
There are probably similar steps for the Intel technology.