Resetting PowerBook and Ibook Power Management Unit (PMU)
Resetting PowerBook and Ibook Power Management Unit (PMU)
Resetting PowerBook and Ibook Power Management Unit (PMU)
, 2010
Article: HT1431
Summary
Learn how to reset the PowerBook and iBook Power Manager. Resetting the power manager also resets date and time settings.
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)".
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:
2. Restart (Control-Command-Power)
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 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)
PowerBook (FireWire)
iBook (16 VRAM), iBook (14.1 LCD 16 VRAM), iBook (14.1 LCD 32 VRAM), iBook (32 VRAM), and 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)
iBook (16 VRAM), iBook (14.1 LCD 16 VRAM), iBook (14.1 LCD 32 VRAM), iBook (32 VRAM), and 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)
iBook (Dual USB), iBook (Late 2001), and iBook (14.1 LCD)
PowerBook G3 (M3553)
3. Press and hold down the power button for 5 seconds and then release the button.
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.
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.
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.
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.
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.
iBook (Dual USB), iBook (Late 2001) and iBook (14.1 LCD)
1. If the computer is on, turn it off.
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.
Reset button on iBook (Dual USB) computer. Note: The red dot shows the button's location. The button is not actually red.
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.
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.
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.)
3. Wait 5 seconds.
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.
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 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.
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.
Additional Information
PowerBook 100 through PowerBook 5300: Resetting Power Management Unit (PMU)
PowerBook G3 Computers: How to Identify Different Models
PowerBook G4 Computers: How to Identify Different Models
iBook: How to Identify iBook Models