Repeated shutting-down after PMU reset

Question

Hello-
Very suddenly I am having problems with my 8/2005 g4 iBook. It has started shutting down while in the sleep mode, so I came here to troubleshoot and found instructions to reset the PMU. I did so, but it continues to shut down. Any suggestions before I bring it to an Apple Care site? I also notice that the power cord shows a green light even if I remove the battery during this time (I tried removing the battery & turning on before I tried resetting the PMU). Otherwise, the computer seems to be fine, albeit a little slower than it was a year ago.
Thank you much!

Answer 1

That's an odd set of symptoms; and I wonder if the cause was something
else before the PMU reset sequence. You did the PMU with computer off,
as per AppleSupport document #14449 instructions - and it shuts down.
Not sure if something like the PRAM/NVRAM (one or both) could be
corrupted. The resets for these require different procedures. A variety
of things could be the cause of a sudden shutdown, to include some
hardware items in addition to the non-volitile ram, and parameter random
access memory. A sudden shutdown in some different models involved
other factors not reported alot in the iBookG4. The Intel® MacBook uses
a different technology so its sudden shutdown on a few models was CPU
heat buildup in some known examples; when proven to not be lesser causes.
Sudden shutdown symptoms can mimic more common causes of system
failure (bad RAM, improperly seated RAM, improperly seated hard drive,
bad software install, bad battery, bad AC adapter, corrupted PRAM,
corrupted NVRAM) which ALL must be ruled out. Since you have Apple
Care, any hardware component failures would be covered. Did you try
running the Apple Hardware Test from the boot/install DVD? It may not
catch this kind of problem, but you could tell the technician you ran it.
I have not run mine, but hear you boot from the install disc #1 and hold
the Opt key down and then after awhile you'd get a choice of startup items.
Did you upgrade the RAM lately? Some poorer RAM may cause issues;
but usually kernel panic activity is seen with bad RAM in the user slot.
If the strange behavor occurred after a step update from 10.4.7 to 4.8,
some users would try the Combo large update file installed over it all;
being sure to repair disk permissions before & after all software updates.
But the symptoms don't necessarily point that way.
You should try to archive your personal stuff on to some media outside
of the computer's hard drive; in case some tech has to wipe the drive or
do something else to the machine while it is away for repairs. If you have
an external FireWire enclosed drive, you may try making a clone of it all.
One level of troubleshooting may include using Disk Utility's tools on the
boot installer disc and totally wiping/zeroing data/reformatting the HDD.
This is where a bootable clone of your whole hard drive would be handy;
to make a full restoration back to the computer's drive afterward.
Hopefully someone with less drastic (and less wordy) ideas will offer them!