Apple PMU Forced shutdown message

Question

Apple PMU Forced shutdown message

I just purchased a used Quicksilver 2002 model. Been having some intermittent power shutoff problems (kernel message asking to press power button for several seconds until shutdown), also some kernel issues with a Griffin PowerMate knob (which has since been unplugged)- it has shut down 4 times in the last 20 minutes. System log reports this all 4 times:

Dec 31 18:00:34 localhost kernel[0]: ApplePMU::PMU forced shutdown, cause = -122

Two of the four times, I was installing some software; the other two times it was just sitting there, running nothing but the OS. Interesting that all other time stamps in the system log showed the correct date and time, but this one above is off. Could this be the PMU battery (you know, that little battery that plugs into the motherboard)?

G4 Quicksilver 2002 2x 1GHz, 1GB RAM | PowerBook 15" 1.5Gh (Leopard)z, Mac OS X (10.4.11), iPhone 8GB- v2.1

Posted on Oct 8, 2008 3:40 PM

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Answer 1

Oct 8, 2008 5:44 PM in response to Terry Smelker

Hi! No it is not the battery. The battery only provides a trickle of power to startup. Usually forced pmu shutdowns are caused by bad power supplies and/or heat issues such as a fan in the psu not working. Tom

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Answer 2

Oct 8, 2008 6:23 PM in response to Terry Smelker

Thanks, Thomas, for the response. I reset the PMU and turned the unit on and let it run with no apps running, it's been on for an hour now with no shutdowns. However, I did a visual check on the back and noticed that the fan that exhausts out thru the panel where the ethernet, speakers, USB, etc. plug in (part of the access panel door) isn't running. I think this is the fan that cools the CPU; for the length of time the unit's been running now, that fan should be spinning. I've got an appointment at the local Genius Bar early tomorrow morning; hopefully, they can help narrow this down.

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Answer 3

Oct 8, 2008 7:34 PM in response to Terry Smelker

Hi, sounds to me like you're having kernel panics - which are quite likely caused by some bad hardware.

The PMU forced shutdown is most likely to simply be a record of you holding down the power button to turn off the computer, as requested by the frozen machine.

The first thing to try with panics is swapping your RAM chips around - one may be defective. Remove all but one, see if the problem goes away; if not, remove that one & try again with another.

If the issue continues, try running Apple Hardware Test. If no defective hardware is found, you should check out what software you're running - visible or not - as this may well be the cause of your problems.

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Answer 4

Oct 8, 2008 8:59 PM in response to Terry Smelker

Actually, Patrick, the last four times it has shut down today, it didn't prompt me to shut it down via the power button- it simply blinked off. When it has done that, the message stored in the Console is different from the kind that occurs when a kernel panic happens. The kernel panic log does indeed tell me what hardware might be giving it fits- but that hardware has since been left unplugged. This log entry is different- not associated with any hardware, just the PMU message as mentioned above (there's also no mention of the PMU when I get the kernel panic screen).

The note about testing the memory is a good one though- I'll have to try that. I still tend to think that it is a heat issue or a bad Power Supply- but I can't say for sure yet.

Alas, I can't run the Apple Hardware Test disk- I didn't get any disks with this used machine. I have other AHT disks for other Macs I own, but they're not compatible.

Message was edited by: Terry Smelker

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Answer 5

Oct 8, 2008 9:11 PM in response to Terry Smelker

Hi! You can download the disk image of the hardware test disk for the QS HERE. Tom

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Answer 6

Oct 8, 2008 9:54 PM in response to Terry Smelker

Thank you Tom! That is a valuable resource! I was inspecting my G4 with the access cover down while running, and the CPU fan is definitely not running, even though it is plugged into the MB. I shut the machine down, removed the CPU fan, blew/scraped the copious amounts of caked-on dust from the fan, and spun it a few times- it's definitely got some bad bearings. I put the CPU fan back in the unit, powered the unit up, and the fan spun sluggishly with a gawd-awful grinding noise, then came to a halt. So I know that the CPU fan is bad, which is a simple fix- but I'll still take it to the Genius Bar to see if there's anything else they can come up with.

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Answer 7

Oct 8, 2008 10:14 PM in response to Terry Smelker

Ah righto, yes the fan not spinning will probably be your problem!

Higher-MHz G4s certainly need all the cooling they can get, and a panic or spontaneous shutdown are both good signs of a cooking processor.

Best of luck getting this sorted out as painlessly as possible!

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Answer 8

Oct 9, 2008 3:23 PM in response to Terry Smelker

Okay-dokey, got a new CPU fan and a new PRAM battery installed. Hopefully this will solve the problem. Stay Tuned...

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Answer 9

Oct 9, 2008 5:31 PM in response to Terry Smelker

Hi! One word of caution to readers is NEVER run a machine whose processor fan isn't working because it will fry the processor. Tom

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Answer 10

motsteve

Level 2

225 points

Oct 9, 2008 6:40 PM in response to Thomas Bryant

AMEN, brother!

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