- The computer must be turned off. If it is not, please shut it down prior to beginning.
- Press the power button to power on the computer.
- Immediately after pressing the power button, press and hold the [D] button on the keyboard. Continue to hold down the key until the Apple Hardware Test (AHT) icon appears or the Apple Diagnostics (AD) language selection menu loads.
- At this point, the next step will depend entirely on the version of the utility that loads. For AHT, go to step 4a; For AD, go to step 4b.
- 4a. Once the console is fully loaded, using a mouse or keyboard click the Test button or type in T to begin the self-test. If you wish to perform a more thorough test, check the "Perform extended testing" check box before beginning the test. This examination takes longer to complete, but it provides in-depth checking of RAM addresses and Hard Drive sectors for errors.
- 4b. Once the language is selected, the computer will begin the self test, which takes 2-3 minutes on average. When the test is complete, any issues detected will be listed on the subsequent screen. Helpful links to resolving many of these issues may be included, directly from Apple's support site. Additionally, AD uses reference codes to identify specific issues pertaining to hardware and potential failures. These codes can be used to further breakdown a problem or contact Apple technical support directly from AD.
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