Once in a while, and despite Apple choosing quality components, you may get
a boot issue, graphics issue, or any number of other hardware problems during
normal usage of your Mac. When a problem occurs, follow these steps to narrow
the problem down.
1. Disconnect Your Accessories
In order to rule out any issues with accessories connected to your Mac, you
need to first ensure that all external hard drives, microphones, speakers, and
other accessories have been disconnected from your computer. Only leave the
keyboard, mouse, and monitor connected before proceeding.
If you find that your computer functions normally without any accessories
connected, then you can attach your accessories (one at a time) back to the
computer, until you find the accessory that is the root cause of the issue.
2. Run Apple Hardware Test
Once you've disconnected all accessories, restart your Mac while holding
down the "D" key. If you have a newer Mac (manufactured after June
2013), then you will be immediately launched into the new Apple Diagnostic Tool
(older Macs will be booted into Apple Hardware Test).
While the Apple Diagnostic tests are running, you will be shown a progress bar
and a time estimation. Once the test has been completed, then you will see a
message that will let you know if any issues were found.
If issues were found, then you'll want to write down the reference codes that
are listed, so that you can take it in to AppleCare members and they can
quickly evaluate that part of your computer when taking it in for repair.
You can find a list of the reference codes that can be generated by AHT or
Apple Diagnostics on the Apple support website. This will give
you a better idea of the issues that were found and their meaning.
3. Apple Diagnostics Keyboard Shortcuts
While booting to or within the Apple Diagnostic tool, there are a few
keyboard shortcuts that you can use in order to better navigate the system and
re-run tests.
Option
+ D - Use this when restarting your Mac to load the Apple Diagnostic test from
the Internet
Command
+ G - Shows the Getting Started guide
Command
+ L - Displays the language selection screen
Command
+ R - Re-runs the tests again, often useful to verify a test if issues are
found
S
- Shutdown the Mac
R
- Restart the Mac