How to reset portable Macs power management units
Feb 21, '07 07:30:01AM
Contributed by: aphealy
The keyboard and trackpad completely failed on a friend's MacBook Pro Intel Core 2 Duo 15.4" running OS 10.4. According to Apple tech support, this had something to do with power management, and he gave this procedure to restore functionality, which worked:
After doing this, the machine should then boot up with normal function.
- Remove battery and power adapter.
- Hold down power button for 10 seconds.
- Reinstall battery and attach power adapter.
- Hold down Command-Option-P-R, a total of four keys, and press power button. Don't release the keys.
- Continue holding the four keys until you hear the startup sound twice, then release.
[robg adds: To be completely precise, MacBooks and MacBook Pros manage ppower through the System Management Controller (SMC), and here are Apple's official reset instructions for those machines. For PowerPC portables, power was managed by the Power Management Unit (PMU), and here are those reset instructions. As noted in both articles, resetting the SMC/PMU should always be the fix of last resort.]
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