MBP screen goes dark when power is unplugged

[rdmty]

Hi,

I have a last gen Macbook Pro, and when I *sometimes* unplug the power adapter, it can cause my screen to go dark. In comparison, it's similar to when the brightness level is ALL the way down, i.e. you can still make out the screen, but you have to look very, very hard. Of course turning up the brightness does nothing. The fastest way I have found to fix this is to close the lid so that it goes to sleep and then wake it up again and the brightness will be back to normal.

Anyone know what causes this and how to fix it? Thanks.

 

[kastenbrust]

Have you gone to energy saver preferences in your preferences panel, and changed the settings there?

Out of curiosity whats your battery health?

 

[iLog.Genius]

I'm going to say, it does that to save power. Made a thread asking why everything doesn't run as smooth when plugged in with AC adaptor and it's because things are throttled, this would apply here. You can adjust the brightness back. This can be changed in Energy Saver. Uncheck "slightly dim the display when using this power setting". When you remove the AC adaptor, it will stop dimming.

 

[rdmty]

It is not related to energy savings because:
1) It does not always happen.
2) The screen goes ALL the way dim (lower your brightness all the way down)
3) It happens *instantly* when the cable disconnects.
4) I can not change the brightness levels when this occurs.

It is not the usual action that happens when you disconnect the power adapter (i.e. screen dims a little bit to save power). The screen goes so dark that you can barely read anything.

*edit*
I have changed the "Automatically reduce the brightness of the display before display sleep" option to see if it happens. I can't really reproduce this at all. It just happens sometimes when the power adapter gets unplugged, which leads me to believe this is a bug instead of a functionality.

 

[iLog.Genius]

It is not related to energy savings because:
1) It does not always happen.
2) The screen goes ALL the way dim (lower your brightness all the way down)
3) It happens *instantly* when the cable disconnects.
4) I can not change the brightness levels when this occurs.

It is not the usual action that happens when you disconnect the power adapter (i.e. screen dims a little bit to save power). The screen goes so dark that you can barely read anything.

*edit*
I have changed the "Automatically reduce the brightness of the display before display sleep" option to see if it happens. I can't really reproduce this at all. It just happens sometimes when the power adapter gets unplugged, which leads me to believe this is a bug instead of a functionality.

Try to reset PRAM and SMC and see if this happens.

 

[RITZFit]

Mine does this too. I always assumed it was the energy saving scheme