Clean OS X Install--Keyboard Backlighting not Working

[puma1552]

Just did a clean install of OS X on my Air. The keyboard backlighting does not work--when I try to adjust with the F5/F6 keys I just get the circle with the little line through it, and even in a pitch dark room the keyboard does not light up whatsoever.

In system preferences I have the "Illuminate keyboard in low light conditions" box checked and have the slider to "never"

Logic Board??

 

[p.luik]

Do another clean install. PS: probably the most calm person to suggest their logic board is bad.

 

[gr8tfly]

Do you always get the "unavailable" (circle/slash)? Or, does it show the adjustment on-screen, with no illumination?

You could try a SMC reset, but if it's the latter condition, there's a good chance it's a h/w problem. http://support.apple.com/kb/HT1411

 

[puma1552]

It's always unavailable, and the keyboard never lights up regardless of lighting conditions.

Also looking in System Profiler, the keyboard is not listed under hardware, which if I'm not mistaken it should be in there.

Also this happened right after the clean install, and now it is still happening with the update to 10.5.7.

FWIW this issue first started when I installed Windows Vista last week; the keyboard ceased to be adjustable in either Windows or OS X, and due to some other problems I decided to just delete the Windows partition and do a clean install on OS X, but for some reason that problem is still here after doing a clean install with no trace of Windows anywhere.

Also the computer seems to be running 10-15 degrees warmer than it should be. I'm at mid-upper 50's (Celsius) with one Safari browser open and no applications.

 

[gr8tfly]

It's always unavailable, and the keyboard never lights up regardless of lighting conditions.

Also looking in System Profiler, the keyboard is not listed under hardware, which if I'm not mistaken it should be in there.

Also this happened right after the clean install, and now it is still happening with the update to 10.5.7.

FWIW this issue first started when I installed Windows Vista last week; the keyboard ceased to be adjustable in either Windows or OS X, and due to some other problems I decided to just delete the Windows partition and do a clean install on OS X, but for some reason that problem is still here after doing a clean install with no trace of Windows anywhere.

Also the computer seems to be running 10-15 degrees warmer than it should be. I'm at mid-upper 50's (Celsius) with one Safari browser open and no applications.

It sounds like a corrupt SMC - I still think resetting it is worthwhile. It also controls the fans.

I haven't run the AHT on a MBA - I don't think it tests the kybd backlight, but you can run it by holding down the "D" on startup. On a MBA, the AHT is stored on the hard drive, though you can also use Disk 1 (Disk 2 on the Late 2008 MBA) and an external optical drive.

 

[puma1552]

An SMC reset unfortunately fixed neither problem.

I may try the AHT on the next startup.

Also in looking in my macbook pro, the keyboard is not listed in system profiler--my mistake.

 

[stoconnell]

An SMC reset unfortunately fixed neither problem.

I may try the AHT on the next startup.

Also in looking in my macbook pro, the keyboard is not listed in system profiler--my mistake.

The keyboard is off the USB bus.. here is the excerpt from running system_profiler in terminal window.

USB Bus:

Host Controller Location: Built In USB
Host Controller Driver: AppleUSBOHCI
PCI Device ID: 0x0aa5
PCI Revision ID: 0x00b1
PCI Vendor ID: 0x10de
Bus Number: 0x04

Apple Internal Keyboard / Trackpad:

Product ID: 0x0223
Vendor ID: 0x05ac (Apple Inc.)
Version: 0.73
Speed: Up to 12 Mb/sec
Manufacturer: Apple Inc.
Location ID: 0x04600000
Current Available (mA): 500
Current Required (mA): 40

 

[gr8tfly]

An SMC reset unfortunately fixed neither problem.

I may try the AHT on the next startup.

Also in looking in my macbook pro, the keyboard is not listed in system profiler--my mistake.

Given the timing of when it went out, I tend to think it's software - but, I can't think of anything else you can reset, except for the PRAM. A SMC reset should clear that anyway, sooo...

If it is hardware, it could be something as simple as reseating a cable. Since the backlight shows as "unavailable", that would indicate the ambient sensor is "stuck" at a high light level. The cable that carries the ambient light sensor data and power is accessible by removing the bottom cover - something an Apple tech might be able to do while you wait. I'll keep my fingers crossed for it to be an easy fix

 

[itou]

mine's screwed up too.

 

[charliex5]

My wife's MacBook Pro has the same problem. We've been trying to figure it out to no avail...

 

[gr8tfly]

My wife's MacBook Pro has the same problem. We've been trying to figure it out to no avail...

Interesting - my brother-in-law's 2.33 MBP is not working either. However, in his case, it's not stuck with the "unavailable" icon displayed. When trying to adjust the brightness, he get feedback through the on-screen icon (it "goes up and down"), but the backlight remains out. I had him do a clean Leopard install - no difference. At this point I decided it's a hardware problem and time for a trip to the Genius Bar.

Have either of you (charliex5 or itou) had the same symptom? Or are yours stuck with the "unavailable"?

 

[charliex5]

Yeah, the icon on the computer changes but the light doesn't come on.

 

[gr8tfly]

Yeah, the icon on the computer changes but the light doesn't come on.

Very interesting. That's the same as his (and different than the OPs).

Have you tried the above suggestions, too? (SMC reset, clean install)

Also, which model MBP?

Thanks. It sure would be nice if it were software, and could save him the time/trip to Apple.

 

[itou]

Have either of you (charliex5 or itou) had the same symptom? Or are yours stuck with the "unavailable"?

i don't have it as "unavailable", i can turn it up and down but it's not automatic.

 

[gr8tfly]

i don't have it as "unavailable", i can turn it up and down but it's not automatic.

Thanks - so same as charliex5.

 

[qubex]

I had a somewhat similar problem with my MacBookPro recently: the hardware volume keys no longer worked after an OS re-install.

I fixed it by doing a full permissions repair.

(You might find it useful to boot into single-user mode and use AppleJack to repair permissions on certain system files that are usually locked for changes.)