How To Reset PowerBook and iBook Power Management Unit (PMU)

The power manager is basically a computer chip that is present on the logic board of the PowerBook and iBook. As the name suggests, it is liable for the power management control of the system. So it controls hard disk spin down, sleep and wake, backlighting and other activities related to computer sleeping.

With the passage of time, the Power Manager settings may get inoperative and pose different problems to the computer. The problems include not turning on, uncharged battery, and insensitivity to AC adapter, etc.

Resetting the power manager:

Resetting the power manager should be taken as a last solution as it permanently removes the RAM disk and all of its contents. So you should only opt for it if you suspect the hardware failure of the Power Management System.

What it does is that it basically returns the iBook and PowerBook hardware to default settings and shut down the computer forcefully. So if ever the computer gets unresponsive then try to get over it by restarting it. If restart does not work then try the following steps.

  1. Force Shut Down (press the power button for 10 seconds)
  2. Force Quit (Option-Command-Escape)
  3. Restart (Control-Command-Power)

If still any of the above steps does not work then for further correspondence you can visit

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