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I have to do a PMU reset to turn on my G4 PowerBook (1.25 GHz). This occurs on every shutdown of the system.

What are potential causes of this?

I'm perfectly happy to troubleshoot, but on Google I'm hitting a lot of misinformation.

I notice that my battery also has 0 Remaining capacity (From System Profiler), even though it only has 125 cycles on it (i.e. not charging). Not sure if this is important, but thought I would throw it in there.

More Info:

  • Did reset-nvram & reset-all from open firmware first
  • Sleep: light flashes on front, never wakes back up. (Have to PMU reset)
  • Battery Removed: still have to reset PMU after each shutdown.
  • Removed PRAM Battery: still have to reset PMU after each shutdown.
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Do you mean G4 PowerBook? The MacBook line (including the Pro) was introduced with the Intel processors. – CajunLuke May 11 '11 at 21:31
Thanks -- Yes I did. – dpb May 11 '11 at 22:23
Can you sleep the machine (when you close the lid, what happens)? When it's asleep, what happens when you pull the power cord? Can you run the machine on battery? What does it display when you run it plugged into the wall but with no battery in? – CajunLuke May 11 '11 at 22:49
Given the system's age... If there was a long period (12 months or more) during which the computer was unused, you might consider trying a new battery. Actually, you might want to try a new battery anyway -- their expected lifespan is about a year or two of regular use, and almost always less than three years under optimal conditions. – Austin May 12 '11 at 4:20

Sounds as if your PRAM battery needs replacing... Assuming you have a A-1046 G4 Powerbook which does have a PRAM battery and you are losing the time setting I would try the PRAM battery first. It is a simple job and the cheapest quick check.

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