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Archived - Resetting PowerBook and iBook Power Management Unit (PMU)

Learn how to reset the PowerBook and iBook Power Manager. Resetting the power manager also resets date and time settings.

Note: If you have an Intel-based Mac notebook, see Intel-based Macs: Resetting the System Management Controller (SMC) for informaiton on resetting the SMC which replaces the PMU.

This article has been archived and is no longer updated by Apple.

After the reset, on some iBooks and PowerBooks, the system clock is set to 00:00 (GMT), 01 Jan 1970 for computers with Mac OS X or 00:00, 01 Jan 1904 for computers with Mac OS 9.

This article refers to Apple products manufactured November 1997 or later. For products manufactured before that date, see "PowerBook: Resetting Power Management Unit (PMU)".

About the Power Manager

The Power Manager is an integrated circuit (computer chip) that is usually on the logic board of the PowerBook and iBook. As the name implies, it is responsible for power management of the computer. It controls backlighting, hard disk spin down, sleep and wake, some charging aspects, trackpad control, and some input/output as it relates to the computer sleeping.

Over time, the settings in the Power Manager may become unusable, which can result in operational anomalies with the computer. Examples include not turning on, not waking from sleep, not charging the battery, or not seeing the AC Adapter, among others.

Resetting the PMU is not intended for resolution of a stall or situation in which the computer is unresponsive. A PMU reset should not be necessary except as a last resort in cases where a hardware failure of the power management system is suspected. Performing a PMU reset returns the iBook and PowerBook hardware, including NVRAM, to default settings and forces the computer to shut down.

For most situations, a restart is sufficient. If the computer has stopped responding, try these steps, in order, until the computer responds:

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

Only perform a PMU reset on the computer if none of the above steps resolved the situation. If this is the case, see below for instructions on locating the reset button or key combination for your model of iBook or PowerBook. If your computer is earlier than the models listed here, see "PowerBook: Resetting Power Management Unit (PMU)".

Warning: Resetting the Power Manager on any PowerBook or iBook will permanently remove a RAM disk, if present, and all of its contents.

PowerBook and iBook models covered in this document

PowerBook G4 (15-inch 1.67/1.5GHz)
PowerBook G4 (17-inch 1.67GHz)
PowerBook G4 (15-inch Double-Layer SD)
PowerBook G4 (17-inch Double-Layer SD)

  1. If the computer is on, turn it off.
  2. Disconnect the AC Adapter and remove the computer's battery.
  3. Press and hold down the power button for 5 seconds and then release the button.
  4. Reconnect the battery and AC Adapter.
  5. Press the Power button to restart the computer. 

PowerBook G4 (12-inch)
PowerBook G4 (12-inch DVI)
PowerBook G4 (12-inch 1.33GHz)
PowerBook G4 (12-inch 1.5GHz)
PowerBook G4 (15-inch FW 800)
PowerBook G4 (15-inch 1.5/1.33GHz)
PowerBook G4 (17-inch)
PowerBook G4 (17-inch 1.33GHz)
PowerBook G4 (17-inch 1.5GHz)

  1. If the computer is on, turn it off.
  2. Reset the power manager by simultaneously pressing and then releasing Shift-Control-Option-Power on the keyboard. Do not press the fn (Function) key while using this combination of keystrokes.
  3. Wait 5 seconds.
  4. Press the Power button to restart the computer. 

PowerBook G4 (DVI) and PowerBook G4 (1 GHz/867 MHz)

  1. If the computer is on, turn it off.
  2. Disengage the two keyboard latches located between the Esc and F1 keys, and the F11 and F12 keys. (You may also need to disengage the keyboard locking screw located between the F5 and F6 keys.)
  3. Lift the keyboard. To ensure no harmful static electricity is transferred to the computer, properly ground yourself before performing this procedure.
  4. Press and release the reset button located on the upper right side of the logic board near the power button, shown here.
  5. Wait 5 seconds.
  6. Press the power button to restart the computer.

Reset Button

Reset Button on PowerBook G4 (DVI) and PowerBook G4 (1 GHz/867 MHz) 

PowerBook G4 and PowerBook G4 (Gigabit Ethernet)

  1. If the computer is on, turn it off.
  2. Press and release the reset button located on the rear panel of the computer between the external video and modem ports.
  3. Wait 5 seconds.
  4. Press the Power button to restart the computer. 

PowerBook (FireWire)

  1. If the computer is on, turn it off.
  2. Press and release the reset button located on the rear panel of the computer between the external video and modem ports.
  3. Wait 5 seconds.
  4. Press the Power button to restart the computer. 

iBook (16 VRAM)
iBook (14.1 LCD 16 VRAM)
iBook (14.1 LCD 32 VRAM)
iBook (32 VRAM)
iBook (Opaque 16 VRAM)
iBook (Early 2003)
iBook (800 MHz 32 VRAM)
iBook (900 MHz 32 VRAM)
iBook (14.1 LCD 900 MHz 32 VRAM)
iBook G4
iBook G4 (Early 2004)
iBook G4 (Late 2004)
iBook G4 (Mid 2005)

For iBook (16 VRAM) and later models of iBook, there is no physical reset button.

  1. If the computer is on, turn it off.
  2. Reset the power manager by simultaneously pressing and then releasing Shift-Control-Option-Power on the keyboard. Do not press the fn (Function) key while using this combination of keystrokes.
  3. Wait 5 seconds.
  4. Press the Power button to restart the iBook computer. 

iBook (Dual USB), iBook (Late 2001) and iBook (14.1 LCD)

  1. If the computer is on, turn it off.
  2. Disconnect the AC power adapter.
  3. Remove the battery.
  4. Press and release the reset button (shown here) located above the Audio/Video port on the left side of the iBook (Dual USB) computer by inserting the end of a paper clip into the small hole and gently pressing the switch once.
  5. Wait 5 seconds.
  6. Reconnect the AC power adapter.
  7. Put the battery back in the computer.
  8. Press the Power button to restart the iBook computer.

Reset Button

Reset button on iBook (Dual USB) computer. Note: The red dot shows the button's location. The button is not actually red.

Original "flavored" iBook and iBook (FireWire) computers

  1. If the computer is on, turn it off.
  2. Disconnect the AC power adapter.
  3. Remove the battery.
  4. Press and release the reset button (shown below) located above the Power button at the base of the display. Use a small, blunt instrument such as a paper clip to press the button.
  5. Wait 5 seconds.
  6. Reconnect the AC power adapter.
  7. Put the battery back in the computer.
  8. Press the Power button to restart the iBook computer.

Reset Button

Original "flavored" iBook and iBook (FireWire) reset button

PowerBook G3 Series (Bronze Keyboard) (M5343)

  1. If the computer is on, turn it off.
  2. Press and release the reset button on the rear of the computer. The reset button is located between the external video and modem (RJ-11) ports.
  3. Wait 5 seconds.
  4. Press the Power button to restart the PowerBook computer.

Note: When you reset the Power Manager, wait at least 5 seconds before pressing the Power button to start up the computer. If you do not wait at least 5 seconds, the reset procedure may fail. (If you suspect that the reset procedure has failed, press and release the reset button again and wait 5 seconds before pressing the Power button.) 

PowerBook G3 Series (M4753)

  1. If the computer is on, turn it off.
  2. Simultaneously press Shift-Fn (function)-Ctrl (control)-Power.
  3. Wait 5 seconds.
  4. Press the Power button to restart the PowerBook computer.

PowerBook G3 (M3553):

The PowerBook G3 (M3553) has two different ways to reset the Power Manager. The first is to use the reset button to the left of the Serial port.

Resetting the Power Manager

  1. If the computer is on, turn it off.
  2. Restart the computer by holding down the reset button to the left of the Serial port for 10 to 20 seconds.
  3. If the computer does not restart, repeat step 2 three or four times.

Resetting the Power Manager and PRAM

Resetting the parameter RAM (PRAM) when the computer is shut down also resets the Power Manager. The following process resets both the Power Manager and the parameter RAM.

  1. If the computer is on, turn it off.
  2. Make sure the Caps Lock key is not down.
  3. Restart the computer. Immediately after hearing the startup sound, simultaneously press and hold Command-Option-P-R. (If you do not hold down the key combination within 5 to 10 seconds after the computer restarts, you must repeat steps 1-3.)
  4. Hold down the keys until you hear the startup sound again. Then release the keys.
  5. If the computer shuts itself off, press the reset button on the back of the computer to turn it back on.
  6. When the computer has finished starting up, restore any custom settings for the desktop pattern, memory, network, AppleTalk, trackpad, power conservation, and so forth.
Last Modified: Jul 17, 2013
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  • Last Modified: Jul 17, 2013
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