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Question: Kernel Panic - invalid backlight duty cycle - after upgrade from 10.5.2 on macbook air A1237

Here is the short version. I bought an older orignial Macbook Air Model A1237. The hinges had been damaged, and the screen would not display correctly - it had lines all across it and you could not see what you were doing. Anyway - I replaced the screen, hard drive, logic board, upper case, pretty much everything in sucession in an effort to get the MBA up and running again and get rid of the kernel panic I keep getting, all Apple replacement OEM parts. I bought a replacement screen - making sure I checked compatibility etc.. but when it started up I felt great perfect view - all was good - then it kernel paniced. I finally figured out that if I turned up the backlight manually all the way to max or if the ambient sensor made the backlight go to max - these were the only time I get a panic. Otherwise it runs perfeclty. The odd thing is I bought the original MBA disc that would have came with the MBA brand new - and if I wipe the hard drive and install leopard 10.5.2 from the dics and do not update anything - it works 100% perfectly no kernel panic at all. If I updgrade beyond the 10.5.2 I get the panic back. So that tells me its not the hardware, and I have confirmed the hardware and firmware are all up to date, as I was hoping it would be that easy a fix of updating the firmware. I have tried everything - googled everything - I am at the end of my rope on this one - please help.

In addition to all the repair work - i have tried test user, upgrading to snow leopard and lion, taking to the apple store, everything I can do , with no solid answer - the apple store told me it was hardware. But if it was then 10.5.2 should generate the panic as well. There are lots of articles and posts on other forums on this very issue - usually surrounding having the MBA display repaired and then they started getting the panics thereafter - but no one has ever recieved an answer either at all, or that works.

Here is the KP log below - please let me know your thoughts - id like to upgrade to lion to get the most out of the MBA - any help is appreciated - - - - - heres the log - - - - ( the reason the BSD states at loginwindow is the ambient sensor at that time kicks in and creates the panic ):

Interval Since Last Panic Report: 3873 sec

Panics Since Last Report: 1

Anonymous UUID: 3A665154-0D6B-4EDF-8F76-80C322CF134A

Mon Aug 27 23:04:07 2012

panic(cpu 0 caller 0x2E42320C): "IG: Invalid backlight duty cycle value"@/SourceCache/GraphicsDrivers/GraphicsDrivers-5.48.6/Common/GLKernel/Inte l/IntelIntegratedFramebuffer/IntelGMAX3100FB.cpp:7065

Backtrace (CPU 0), Frame : Return Address (4 potential args on stack)

0x2e3dbaa8 : 0x12b4c6 (0x45f91c 0x2e3dbadc 0x13355c 0x0)

0x2e3dbaf8 : 0x2e42320c (0x2e431258 0xa4aa 0x2e3dbb18 0x0)

0x2e3dbb18 : 0x2e425434 (0x3af6c00 0x5f40 0xe 0x0)

0x2e3dbb68 : 0x2e4d2283 (0x3e75000 0x0 0x626b6c74 0x5f40)

0x2e3dbbd8 : 0x2e3f9769 (0x4639e00 0x4107280 0x3a6ace0 0x80)

0x2e3dbc08 : 0x2e3f724c (0x48f2a00 0x4107280 0x3a6ace0 0x80)

0x2e3dbc38 : 0x2e3f785d (0x48f2a00 0x80 0x2e3dbc68 0x3f158d)

0x2e3dbc58 : 0x2e3f71db (0x48f2a00 0x80 0x2e3dbc88 0x3f0942)

0x2e3dbc78 : 0x2e3f9475 (0x48f2a00 0x430c640 0x3a6ace0 0x80)

0x2e3dbca8 : 0x2e3f92b9 (0x48f2a00 0x430c640 0x3a6ace0 0x80)

0x2e3dbd28 : 0x440edf (0x48f2a00 0x3feb880 0x44 0x11e7de)

0x2e3dbd78 : 0x18b71a (0x48f2a00 0x3fea900 0x44 0x407c7c0)

0x2e3dbdb8 : 0x12d4d6 (0x3b92090 0x407c79c 0x2e3dbdf8 0x11f1c6)

0x2e3dbdf8 : 0x1264fa (0x3b92000 0x392e984 0x408226c 0x0)

0x2e3dbf08 : 0x198fa3 (0x2e3dbf44 0x0 0x0 0x0)

0x2e3dbfc8 : 0x1a1cfa (0x398d120 0x0 0x1a40b5 0x3dc0c80)

Backtrace continues...

Kernel loadable modules in backtrace (with dependencies):


dependency: com.apple.iokit.IONDRVSupport(1.7.3)@0x2e435000

dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000

dependency: com.apple.iokit.IOGraphicsFamily(1.7.3)@0x2e3f5000


dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000

dependency: com.apple.iokit.IOGraphicsFamily(1.7.3)@0x2e3f5000

dependency: com.apple.driver.AppleSMC(2.3.1d1)@0x2e412000

dependency: com.apple.iokit.IOACPIFamily(1.2.0)@0x2e2ec000


dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000

BSD process name corresponding to current thread: loginwindow

Mac OS version:


Kernel version:

Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386

System model name: MacBookAir1,1 (Mac-F42C8CC8)

System uptime in nanoseconds: 58935778708

unloaded kexts:


loaded kexts:

com.apple.driver.AppleHDAPlatformDriver 1.7.1a2 - last loaded 45739893296

com.apple.driver.InternalModemSupport 2.4.0

com.apple.iokit.IOBluetoothSerialManager 2.1.9f10

com.apple.filesystems.autofs 2.0.2

com.apple.driver.DiskImages 199

com.apple.driver.AppleHDAHardwareConfigDriver 1.7.1a2

com.apple.driver.AppleHWSensor 1.9d0

com.apple.driver.AppleUpstreamUserClient 2.7.5

com.apple.Dont_Steal_Mac_OS_X 6.0.3

com.apple.driver.AppleHDA 1.7.1a2

com.apple.driver.ApplePlatformEnabler 1.0.2d1

com.apple.driver.AppleGraphicsControl 2.8.15

com.apple.driver.AppleIntelGMAX3100 5.4.8

com.apple.iokit.IOSCSIArchitectureModelFamily 2.1.1

com.apple.driver.AppleIRController 113

com.apple.driver.AirPortBrcm43xx 367.91.22

com.apple.kext.AppleSMCLMU 1.4.5d1

com.apple.driver.AppleLPC 1.3.1

com.apple.driver.AppleTyMCEDriver 1.0.0d28

com.apple.driver.AppleHDAController 1.7.1a2

com.apple.driver.SMCMotionSensor 2.1.1d2

com.apple.driver.AudioIPCDriver 1.0.6

com.apple.driver.ACPI_SMC_PlatformPlugin 3.4.0a17

com.apple.driver.AppleBacklight 1.6.0

com.apple.driver.AppleIntelGMAX3100FB 5.4.8

com.apple.driver.AppleUSBTCButtons 1.7.4f1

com.apple.driver.AppleUSBMultitouch 189.35

com.apple.driver.AppleUSBTCKeyEventDriver 1.7.4f1

com.apple.driver.AppleUSBTCKeyboard 1.7.4f1

com.apple.driver.BroadcomUSBBluetoothHCIController 2.1.9f10

com.apple.driver.AppleUSBMergeNub 3.5.2

com.apple.driver.XsanFilter 2.7.91

com.apple.iokit.IOATABlockStorage 2.0.6

com.apple.driver.AppleUSBHub 3.4.9

com.apple.driver.AppleFileSystemDriver 1.1.0

com.apple.iokit.IOUSBUserClient 3.5.2

com.apple.driver.AppleAHCIPort 1.7.0

com.apple.driver.AppleIntelPIIXATA 2.0.1

com.apple.driver.AppleUSBEHCI 3.4.6

com.apple.driver.AppleUSBUHCI 3.5.2

com.apple.driver.AppleEFINVRAM 1.2.0

com.apple.driver.AppleRTC 1.2.3

com.apple.driver.AppleHPET 1.4

com.apple.driver.AppleSmartBatteryManager 158.10.5

com.apple.driver.AppleACPIPCI 1.2.5

com.apple.driver.AppleACPIButtons 1.2.5

com.apple.driver.AppleSMBIOS 1.4

com.apple.driver.AppleACPIEC 1.2.5

com.apple.driver.AppleAPIC 1.4

com.apple.security.seatbelt 107.12

com.apple.nke.applicationfirewall 1.8.77

com.apple.security.TMSafetyNet 3

com.apple.driver.AppleIntelCPUPowerManagement 76.2.0

com.apple.BootCache 30.4

com.apple.iokit.IOSerialFamily 9.4

com.apple.driver.DspFuncLib 1.7.1a2

com.apple.iokit.IO80211Family 216.1

com.apple.iokit.IONetworkingFamily 1.6.1

com.apple.iokit.IOHDAFamily 1.7.1a2

com.apple.iokit.IOAudioFamily 1.6.9fc5

com.apple.kext.OSvKernDSPLib 1.1

com.apple.driver.IOPlatformPluginFamily 3.4.0a17

com.apple.iokit.IONDRVSupport 1.7.3

com.apple.driver.AppleSMC 2.3.1d1

com.apple.iokit.IOGraphicsFamily 1.7.3

com.apple.iokit.IOUSBHIDDriver 3.4.6

com.apple.driver.AppleUSBBluetoothHCIController 2.1.9f10

com.apple.iokit.IOBluetoothFamily 2.1.9f10

com.apple.driver.AppleUSBComposite 3.2.0

com.apple.iokit.IOStorageFamily 1.5.6

com.apple.iokit.IOAHCIFamily 1.5.0

com.apple.iokit.IOATAFamily 2.0.1

com.apple.iokit.IOUSBFamily 3.5.2

com.apple.driver.AppleEFIRuntime 1.2.0

com.apple.iokit.IOSMBusFamily 1.1

com.apple.iokit.IOHIDFamily 1.5.5

com.apple.driver.AppleACPIPlatform 1.2.5

com.apple.iokit.IOACPIFamily 1.2.0

com.apple.iokit.IOPCIFamily 2.6

MacBook Air, Mac OS X (10.5.8), 1.6Ghz Intel Core 2 Duo 2gb RAM

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Aug 28, 2012 12:59 PM in response to boss302beav In response to boss302beav

Two thoughts...

Could the logic board be slightly different?

Is there a Kext just for the Backlight or Ambient sensor?

Oh, anyway o edit this value?

@/SourceCache/GraphicsDrivers/GraphicsDrivers-5.48.6/Common/GLKernel/Inte l/IntelIntegratedFramebuffer/IntelGMAX3100FB.cpp:7065

Aug 28, 2012 12:59 PM

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Aug 28, 2012 3:49 PM in response to BDAqua In response to BDAqua

Im not sure if there is a kext for just the backlight or ambient sensor. What do you mean by 0 out the value ? How would I do that ?

I went by the apple store today and they took an hour with me looking at it - but no resolution. They ran the hardware test and it passed all the test. The only thing they recommended was sending it in for flat rate repair - which at this point I am seriously considering if I cannot find a fix.

Please let me know what you mean by zero out the value -

thanks for the response

The logic board is exact same to the original - it is an OEM replacement and the old logic board had same issue - so this has to be something that has been a constant through all the repairs to still exsist.

Aug 28, 2012 3:49 PM

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Sep 11, 2013 8:26 AM in response to arunfromca In response to arunfromca

Your problem may not be exactly the same as that of the original poster of this old thread, and it can be very confusing for everybody if we try to answer more than one question in each thread.

In order for us to give your problem our undivided attention to try to solve it, would you kindly start your own thread, describing the trouble you are having in the fullest detail, including completing your details to show what Mac you are using, what operating system, and what version of the application in question. Please remember to post in the forum relevant to your hardware or version of OS X.

Sep 11, 2013 8:26 AM

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Sep 11, 2013 9:50 AM in response to arunfromca In response to arunfromca

@arunfromca : Sorry for the dealy in completeing the thread with what happended. I finally hit the wall after trying everything I could and taking t to the apple store a few times. In my case my original screen had gone bad and I had replaced the screen with a few differrent ones that weres upposed to be compatible. Apparantly the MBA is very picky and you ahve to have just the right mix of logic board and screen to make it all work and avoid the kernel panic. So the apple store recommended flat repair , which I had not ehard of before. So I took them up on it, and for $300 they replaced everything that needed fixing and it has worked great ever since. So I think it was components in my instance, but thank goodness for the flat repair. I wish you the best and maybe you can get the flat repair if push comes to shove.

Take care,

Sep 11, 2013 9:50 AM

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Mar 9, 2014 9:56 AM in response to boss302beav In response to boss302beav


I had the same problem after I replaced my wife's MBA Original's LCD screen. Suddenly it crashed on boot with a completely light gray/white screen after the logo and the spinning wheel finished (on the point where a normal boot will show the mouse and the login screen will fade in).

I booted on Single User Mode (command + s at boot) and then looked into /Library/Logs/DiagnosticReports, which is where Mac OS X (since v. 10.6) stores the kernel panics. There I found a KP very similar to the one shown by boss302beav.

After some googling -that took me to this thread- and a long investigation -like booting my MBP beside the MBA-, I understood that this problem happened to me on the point that Lion adjust the screen and keyboard lighting, right before showing the login screen.

Fortunately I was much luckier than boss302beav and the stack backtrace ended with the kext that originated it: com.apple.AppleBacklightExpert.kext.

I booted onto single user mode (command +s), then made the filesystem writable: (/sbin/fcsk -fy then /sbin/mount -uw /). And then created a directory called /oldext, and moved the kext there.

mv -r /System/Library/Extensions/com.apple.AppleBacklightExpert.kext /oldext.

Rebooted, and voila, it worked!

You will loose the hability to change the brightness (no slider and brightness keys do not work), but the camera in iPhoto Booth takes snapshots just fine. No problems at all with the camera, and the keyboard lighting works with the keys (not automatically).

Also remember that every time you install an update, this kext will be put back in. Just repeat the procedure and your system will work fine and my wife is happy with her MBA even if it doesn't have brightness controls.

I hope this is useful to anybody with this problem.

Mar 9, 2014 9:56 AM

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Jun 28, 2014 3:42 AM in response to guilleamodeo In response to guilleamodeo

Wow! Thanks! I have been looking for this solution for ages (and many people who replaced their LCD's themselves as well). Almost 12 months ago I replaced the broken hinges of my original MacBook Air and decided to replace my LCD in the progress. Tough luck finding out that Lion wouldn't boot and every other OS except the one it was originally supplied with (10.5.4. as I recall correctly) would kernel panic after adjusting the screen brightness to the highest setting (and using Photobooth & leaving the auto adjustment of screen brightness turned on).

The solution given here by 'guilleamodeo' is working however. Having run 10.6.8 for about a year while not touching that F2 key ever again I decided to upgrade. I had an old copy of 10.7.0 backed up and installed that. Everything was fine after that (the brightness level in my old Snow Loepard install was not 100% and the upgrade to Lion respected that). Upgrading to 10.7.5 made it unbootable however. (Re)moving the 'AppleBacklightExpert.kext' solved it. Take note, my extension was called 'AppleBacklightExpert.kext' and not 'com.apple.AppleBacklightExpert.kext' as in guilleamodeo's solution.

Jun 28, 2014 3:42 AM

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Aug 19, 2014 3:45 PM in response to Marco Bakker X In response to Marco Bakker X

Good evening gentlemen had the same problem with my MBA and found an easy alternative to not having that kind of problem ... Beside the camera on the left side is where is the sensor environment. I picked up a pencil to color in black and spent over the holes to plug the sensor with dust from the pencil did the test with the flashlight from my iphone on top of the sensor and I had no more problem ... worked for me for now I hope that will help you thanks.

Aug 19, 2014 3:45 PM

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Oct 7, 2014 4:42 PM in response to boss302beav In response to boss302beav

So I found a post on a random forum that offered a fix that I have tried and it worked. Background: I had a cracked LCD screen on a A1237, and I replaced a new screen and a battery. I started getting kernel panics when the brightness went to the highest level. Anyways, what you do is you need to get this file from a apple os x 10.5:



Install the .kext file you just grabbed by dragging it into Kext Utility (which can be downloaded here: http://cvad-mac.narod.ru/index/0-4)


Shut down the machine. Reset SMC and PRAM (SMC: http://support.apple.com/kb/ht3964, PRAM:http://support.apple.com/kb/ht1379)

and the problem is fixed. If you google a bit, you can find an os x 10.5.2 AppleIntelGMAX3100FB.kext file at to use.

The original fix I found was posted here:



Just to clarify, my mac book air is running snow leopard 10.6.8, and I inserted the file from a 10.5.2. The fix completely eliminated the problem, now I can turn the brightness to max without the kernel panic.

Oct 7, 2014 4:42 PM

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Question: Kernel Panic - invalid backlight duty cycle - after upgrade from 10.5.2 on macbook air A1237