Surface pro 3 Brightness control missing

I have the same problem. I also tried disconnecting the type cover, reboot and change. But I still can't change then. I have the Surface Pro 3 i7 8gb

I also tried the following methods:

https://www.tenforums.com/tutorials/70157-enable-disable-adaptive-brightness-windows-10-a.html

Option 1: those options aren't available

Option 2: Doesn't work

Option 3: I did this one, but didn't change anything

Option 4: I can't do this because I because there is no Intel Graphics Settings, I tried to install the Intel drivers manually but I can't install them (https://downloadcenter.intel.com/download/28662/Intel-Graphics-Driver-for-Windows-15-40-?product=75114)

https://surfacetip.com/how-to-unlock-power-plans-on-surface-devices/

I changed CsEnabled to 0 in regedit, but that also didn't help

I now do have more power options and I can change them (but there is still no adaptive brightness option). But I can't choose any of the power plans (it gave an error)

https://windowsreport.com/adaptive-brightness-windows-10-wont-turn-off/I did the 5. Disable Adaptive brightness in the Registry but that also didn't help

This is really annoying. I don't want to use adaptive brightness, manual is fine with me. I just want to be able to adjust the brightness. Even on battery saver the brightness looks like it is at full.

the brightness slider can not be moved and is shown dimmed as if it is inactive.

Hmm yes it's still perfectly possible the brightness will fail again for me, but it hasn't yet after a few days :)

Did you try the Surface Diagnostic Tool? Though it didn't fix it itself (in fact it set the brightness to 0%! I suppose it's a solution of sorts if you can use the Surface only in dimly lit locations). The Reset after fixed it.

I realise this is part-black-magic - but it might be worth trying.

This issue makes the Surface into a redundant gadget, if I have to be plugged in I might as well stick with my lovely big 17 inch laptop. It's not as though Microsoft can blame anyone else - they 100% make the hardware and the software.

Previously, I've not used brightness slider on the right panel, but after windows 10 automatic updates adaptive brightness control stopped working and I had to use the slider on the right panel. So I cannot understand why I've paid for that light sensor of adaptive brightness control to be disabled. Microsoft isn't that of the previous quality unfortunately. No solutions on the internet and on this portal helped with the problem.

I tried all of the solutions (about 6) and eventually created a USB Image and reset my Microsoft Surface Pro 3 completely.  The issues were corrected upon re-imaging, but "Windows Update" pushes caused all of the problems to return within 3 days.  

I was taking a trip overseas, and needed to reduce the brightness to preserve battery.  

The USB Re-imaging solution worked for 3 days, and allowed the slider in the right panel to function.   It also allowed the FN-DEL  / FN-Backspace to work temporarily.  

My 4 hours of work to reset my PC was completely undone when windows updated automatically.   The day before my trip, the ability to change the brightness was disabled again.   The problem also affects the "Power and Sleep" settings as well as the allowing the power button to put the device to sleep.  

This is a shame because all of the "Power and sleep" settings are now broken for the device.   There is no ability to preserve battery by adjusting the screen or other functions.   And, even when you get to critical levels, the device continues to burn through the battery like a flamethrower.  

I guess my device is "Plug-in" only until they correct the issue.   I can't even upgrade because the same problem seems to affect Surface Pro 4, 5, etc.