How and when to reset the SMC of your Mac

TechnoAdmin

The System Management Controller (SMC) controls a number of basic Mac functions. The SMC is hardware built into the Mac’s motherboard. Its purpose is to free the Mac’s processor from having to deal with rudimentary hardware functions. With many of the main tasks performed by the SMC, it is not surprising that resetting the SMC to its default state can fix problems.

What the SMC controls

The SMC performs the following functions, which vary by Mac model:

    • Responds to power button presses, including deciding if the press is for power off, sleep, or an accidental misstep by your cat

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    • Detects and responds to the opening or closing of the lid of a Mac notebook
    • Manages the performance of a laptop battery, including charging, calibration and display of remaining battery time

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    • Manages the thermal management of the interior of the Mac by detecting the temperature in various places inside the Mac and then adjusting the fan speed to create or reduce airflow

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    • Uses the Sudden Motion Sensor to respond to the sudden movement of a Mac notebook and take action to prevent damage

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  • Detect ambient light conditions and set proper lighting levels for devices
  • Control the keyboard backlight
  • Controls the screen’s built-in backlight
  • Control the status indicator lights that are present on the Mac
  • Select external or internal video sources on iMacs with video input capabilities
  • Initiates the hard drive spin up and power up sequences
  • Control sleep mode functions
  • Control trackpad functions for Mac models with trackpads

Signs that you need to reset the SMC

Resetting the SMC isn’t a cure-all, but it fixes many of the symptoms a Mac can suffer from, including:

  • Erratic sleep mode performance, including not waking up or going to sleep
  • Entering sleep unexpectedly, even while you are actively working on it
  • Mac notebooks don’t respond to opening or closing the lid
  • No response when pressing the power button
  • Power indicator does not display or displays incorrectly
  • Slow performance, even when Activity Monitor shows low CPU usage
  • Target display mode is not working properly
  • Battery is not charging or is taking too long to charge
  • USB ports not working
  • Wi-Fi hardware missing or not working
  • bluetooth not working
  • Fans running too fast
  • Display backlight does not respond to changes in ambient light level
  • Status indicator lights are not working properly or are stuck in a static state
  • Bouncing Dock icons that keep bouncing without the associated app launching
  • Mac Pro (2013) port lighting won’t turn on or off

How to reset the SMC on your Mac

The method to reset your Mac’s SMC depends on the type of Mac you have. All SMC reset instructions require you to shut down your Mac first. If your Mac doesn’t shut down, try holding down the power button until it shuts down, which usually takes about 10 seconds.

Reset Mac notebooks with user-removable batteries

  1. Shut down the Mac.
  2. Remove the battery.
  3. Press and hold the power button for at least five seconds.
  4. Release the power button .
  5. Reinstall the battery.
  6. Turn on the Mac.

Reset Mac notebooks without user-removable batteries

  1. Shut down the Mac.
  2. On the built-in keyboard (does not work from an external keyboard), simultaneously hold down the Left Shift , Control , and Option keys while pressing the power button for at least 10 seconds. (If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.) Release all keys at the same time.
  3. Press the power button to start the Mac.

Reset Mac desktops and laptops with the Apple T2 chip

If you have a 2018 model iMac Pro or MacBook Pro with the Apple T2 chip:

  1. Shut down the Mac.
  2. Press and hold the power button for 10 seconds.
  3. Release the power button and wait a few seconds.
  4. Press the power button again to turn on the Mac.

As an alternative to iMac Pro with T2 chip, you can:

  1. Shut down the Mac.
  2. Unplug the power cable.
  3. Wait 15 seconds.
  4. Plug in the power cord.
  5. Wait five seconds.
  6. Press the power button to turn on the Mac.

As an alternative to the MacBook Pro with T2 chip:

  1. Shut down the Mac.
  2. Press and hold the right Shift key, the left Options key, and the left Control key for seven seconds. Continue holding them while pressing the power button for another seven seconds.
  3. Release all keys at the same time.
  4. Press the power button to turn on the Mac.

Mac computers (Mac Pro, iMac, Mac mini)

  1. Shut down the Mac.
  2. Unplug the power cable from the Mac.
  3. Wait 15 seconds.
  4. Reconnect the Mac’s power cable.
  5. Wait five seconds.
  6. Start your Mac by pressing the power button .

Alternative SMC reset for Mac Pro (2012 and before)

If you have a 2012 or earlier Mac Pro that isn’t responding to a normal SMC reset, you can force a manual SMC reset by using the SMC reset button located on the Mac Pro’s motherboard.

  1. Shut down the Mac.
  2. Unplug the power cable from the Mac.
  3. Open the side access panel on the Mac Pro.
  4. Just below the drive 4 sled and next to the top PCI-e slot is a small button called SMC . Hold down this button for 10 seconds.
  5. Close the side door of the Mac Pro.
  6. Reconnect the Mac’s power cable.
  7. Wait five seconds.
  8. Start the Mac by pressing the power button .

Now that you have reset the SMC on your Mac, it should work as you expect. If the SMC reset did not fix your problems, you can combine it with a PRAM reset. Although the PRAM works differently from the SMC, it can store some bits of information that the SMC uses.

If you’re still having trouble, you might want to run Apple’s hardware test to rule out a faulty component in your Mac.

TechnoAdmin

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