MacOS High Sierra 10.13.3 MacBook Air登录后触控板及键盘失效求助

Hey there, sorry to hear you're stuck with this frustrating trackpad/keyboard issue on your MacBook Air running High Sierra 10.13.3—especially since you've already tried all the standard fixes like new user accounts, SMC/PRAM resets, and even a fresh system reinstall. Let's focus on that multitouch kernel extension anomaly you mentioned, as it's almost certainly tied to the problem. Here are targeted steps to diagnose and fix this:

1. Verify Multitouch Kernel Extension Status #

First, you'll need an external keyboard/mouse to access the system (since your built-in ones fail post-login). Once you're in:

• Open Terminal and run this command to check if the multitouch kexts are loading properly:

  kextstat | grep -i multitouch
  

• You should see entries for AppleMultitouchTrackpad.kext and AppleUSBMultitouch.kext. If they're missing, show an error, or have a non-zero exit code, that confirms the kexts are corrupted or failing to load.

2. Replace Corrupted Multitouch Kernel Extensions #

If the kexts are damaged, you'll need to replace them with working copies from a known-good source:

1. Grab the two kexts (AppleMultitouchTrackpad.kext and AppleUSBMultitouch.kext) from:
   • A working MacBook Air running the exact same High Sierra 10.13.3 version, or
   • Extract them directly from the High Sierra 10.13.3 installation USB/dmg.
2. Boot into Recovery Mode (hold Command + R on startup), open Terminal, and mount your system drive (use diskutil list to find its name, then diskutil mount /dev/[disk identifier]).
3. Copy the working kexts to the system extensions folder:

   cp -r /path/to/working/kexts/AppleMultitouch*.kext /Volumes/[Your System Drive Name]/System/Library/Extensions/
   

4. Fix file permissions and rebuild the kernel cache:

   chmod -R 755 /Volumes/[Your System Drive Name]/System/Library/Extensions/AppleMultitouch*.kext
   chown -R root:wheel /Volumes/[Your System Drive Name]/System/Library/Extensions/AppleMultitouch*.kext
   kextcache -u /Volumes/[Your System Drive Name]
   

5. Reboot your Mac and test the trackpad/keyboard.

3. Check for Hardware Connection Issues #

If the software fixes don't work, it's time to rule out hardware:

• The built-in trackpad and keyboard on this generation of MacBook Air connect to the motherboard via a thin ribbon cable. Over time, frequent opening/closing can loosen this cable or cause it to wear out.
• If you're comfortable with basic repairs, you can open the bottom case (use a P5 Pentalobe screwdriver) and check if the cable connecting the trackpad/keyboard is securely seated in its motherboard connector. If it's loose, reattach it firmly.
• If re-seating doesn't help, the cable or trackpad/keyboard module itself may need replacement.

4. Verify System Integrity Protection (SIP) Status #

Sometimes disabled or misconfigured SIP can prevent critical kernel extensions from loading correctly:

1. Boot into Recovery Mode, open Terminal.
2. Check SIP status with:

   csrutil status
   

3. If it shows disabled, enable it with:

   csrutil enable
   

4. Reboot and test again.

内容的提问来源于stack exchange，提问作者Pushpendre