brightness slider and brightness fn keys not working

BoA · #1 April 30th, 2005, 12:15 PM

This thread is running on the Apple Support forum as well... thought I'd cross post for another audience looking for possible solutions.

The issue is with the brightness keys and the brightness slider controls. It appears that after the 10.4 upgrade the main LCD on some PBs and iBooks stops working. In my case the attached screen lost the ability to adjust brightness... but my external 20" LCD is fine.

It looks like two things have happened... the association between the keys (F1 and F2) and the code for controlling brightness somehow got disconnected... and/or... the "capability" of the mac to adjust the brightness of the attached LCD got lost in the upgrade.

We've tried repair permissions, rebooting, new users... to no avail... right now this isn't a big issue... but it is annoying....

Bo...

chase · #2 July 11th, 2005, 11:12 AM

After applying a patch to Tiger, I found my brightness and sound control keys on the keyboard were non-operational at some indeterminate time (meaning I rebooted the laptop several times and eventually noticed that my sound and brightness keys weren't working)

Curiously, while the brightness and sound control keys were not working, I also noted the brightness slider control was missing form the System Preference Panel for Display. Others have noted this issue as well [1] -- but I couldn't get a login account on their site to post a response [1] -- which is why I am posting it here on MacFixit.

I have a proposed workaround to this problem.

My workaround is to reboot the machine, and during the reboot process, tap on any of the brightness or sound keys once every two seconds.

However, this is the strangest part: I've replicated my workaround three times. Which means I re-created the problem wherein the sound and brightness keys weren't working.

I'm not 100% clear on the relationship, but I managed to re-create the problem by removing an Application (SimonSays) from my dock. Upon reboot and loggin in, the hardware keys for brightness and sound would not work, *and the Application I had removed previously was again in the dock.*

Furthermore, I noticed the following error message in the console:
2005-06-28 21:29:51.008 loginwindow[86] *** Assertion failure in -[NSThemeFrame initWithFrame:], AppKit.subproj/NSView.m:709
2005-06-28 21:29:51.008 loginwindow[86] Uninitialized rectangle passed to [View initWithFrame:].

Finally, a last surprise : I can no longer re-create the problem -- because I finally managed to remove the Application (SimonSays) from the dock -- and it remained off the dock after reboot. What I did was to log in, disable all startup items in my login prefs. Then I logged out and logged in again. I then removed SimonSays and logged out. And I rebooted. After reboot, I logged in and SimonSays was off the dock and the sound and brightness keys were working.

In closing : I don't believe the root cause is SimonSays, but there is a relationship between a Dock corruption (?) issue and the loss of the hardware keys and that of the slider control in the panel. Tapping on the sound or brightness keys once every two or three seconds during reboot revivies them. Note: you don't have to tap on the keys for every reboot -- just once will do it.

Notes:

Zammy-Sam · #3 July 12th, 2005, 07:13 AM

I didn't read the long post from chase and I might repeat what he said.
Did you check your settings in the System Preferences -> Keyboard & Mouse under the first tab 'Keyboard' for "Use the F1-F12 keys to control.."?

anamorphic · #4 February 4th, 2007, 11:44 AM

Thanks Chase. Your solution worked for me. Very helpful. Still no idea what caused the problem though.

SkippyThorson · #5 August 13th, 2009, 12:31 AM

Yes, it is now 4.25 years since this thread began, and I have reached my boiling point with this issue. My iBook G4 refuses to respond to F1 - F5 (the brightness and volume), and nothing will allow this to work again.

Has anyone come up with some sort of simple patch or solution to this since then? Someone please say yes. Any advice at all? It just up and croaked. No reason. Other than to annoy me, naturally.

dsinclair · #6 September 5th, 2009, 01:51 PM

I had the same problem and after years of frustration fixed it. It's not the checkbox on the function keys preference as some have suggested.

I did 2 things simultaneously so I cant say which actually worked but both are simple. Using spotlight find every folder named "PlugIn" and rename it "Plugin". My macbook pro had 2 of these. Restart and when the desktop comes up during reboot, hit the volume and brightness keys ever 0.5 seconds or so. Fixed.