Why can't I adjust my brightness?


I just finished replacing my battery and wifi card. Some time ago, I had replaced the screen assembly. Since then, the computer had been sitting unused in a drawer.

My brightness will not adjust. It is also somewhat dim. The buttons work, but when I adjust the brightness it stays exactly the same from one bar all the way to the max, although the screen will turn off if I take it down to zero bars.

I have reinstalled a fresh copy of the OS, and updated the software. I have reset the PRAM. I have reset the SMC. I have disconnected, then reconnected and reseated the screen connectors. Still, the problem will not go away.

After resetting the PRAM, the screen was momentarily at what appeared to be max brightness, but then dimmed itself again.

Any ideas? The computer is usable except in bright light, but I do want to have it perfect, especially after all the repairs I’ve done to it.

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If you can't adjust your keyboard's brightness manually, it's likely because you're in a very bright environment and you have your Mac set to automatically adjust the brightness. In this case, the backlit keyboard turns off. When you move to a location with less light, you can once again adjust the keyboard's brightness.

Otherwise if you just prefer using your mouse–you can adjust brightness in OS X and see if it is working.


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I meant the screen brightness! I don't actually have keyboard backlighting on this computer.

Using the slider in preferences gives me the same effect. No adjustment, but if I slide it all the way down, the screen turns off...

Auto brightness is off.


@ivanmorgado It is more like a hardware issue. Did you try moving the display back/forth while the light was off, if so did it flicker at all? This would be a failing inverter board. However theres a chance it could be the LCD panel, the logic board , the LVDS cable or the inverter cable.




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