Chosen Solution
I have a PowerBook G4 1.25GHz. It will not wake from sleep or start from a shutdown without doing a PMU reset. What is the most likely problem? Bad motherboard? Bad PRAM battery? Each time I reboot after a PMU reset I have to reset the time as well as re-enter my airport password.
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. PowerBook G4 Aluminum 15" 1-1.5 GHz PRAM Battery Replacement
