Auto for mac. The Sleep Indicator Light (SIL) on your MacBook, MacBook Air, and MacBook Pro has different behaviors based on the state of your Mac. These behaviors also occur on some iMac, Mac mini, and Mac Pro models, though not all Macs have a SIL.

1. Macbook Pro Green Lights
2. Macbook Pro Green Light Blinking

After you press the power button

Every time you turn on your Mac, it performs various hardware checks, known as a Power-On Self-Test (POST).

If the SIL flashes one or more times after you turn on the computer, and the pattern repeats after a brief pause, the computer may not have successfully passed POST.

• If your computer has hardware issues during POST, it might use a combination of audible tones and blinking SIL behavior to communicate POST issue codes.
• To find the cause of a POST issue, see Intel-based Mac Power On Self Test RAM error codes.

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