How to Clear the PMU on a Mac

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By John Ford
eHow Contributing Writer

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Resett the PMU on Your MacBook or MacBook Pro to Toubleshoot System Issues

Resetting or clearing the PMU (Power Management Unit) or SMU (System Management Controller) on your Mac is one “last ditch” effort available if you’ve been experiencing trouble with your Mac. The SMU is the chip on your Mac that oversees power management, controls backlighting, hard disk spin down, sleep and other Mac system functions. In this lesson we’ll learn how to reset the PMU/SMU on your MacBook or MacBook Pro.

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Difficulty: Easy

Instructions

How to Clear the PMU on a MacBook or MacBook Pro

Step 1

Quit all of your active applications and shut down your Mac.
Step 2

Once your computer is completely shut down, disconnect the computer's AC power Adapter and remove the battery from your Mac.
Step 3

Press and hold down the power button on your MacBook or MacBook Pro for at least five seconds and then release the power button.
Step 4

With your Mac still shut off, reinstall the battery in your MacBook or MacBook Pro and reconnect the AC Adapter. The PMU/SMU has now been reset on your computer.