I know I haven’t posted in a year or so but this bit of information seemed important enough to share.
I was helping a family friend fix their 160GB iPod and Google searches proved fruitless so I thought I’d share the issue as well as how it was fixed.
iPod appears in Finder (equivalent of Windows Explorer) but does not appear in iTunes.
Things tried that didn’t work:
Ejecting the iPod drive that appears in Finder causes iPod to disconnect and then instantly reset, almost as if it ran into a fatal error.
In Disk Utility I erased the drive partition and then ejected the iPod drive. The iPod then appeared in iTunes and worked normally including an update.
The iPod drive appeared to be formatted to FAT and was using up the entire space available on the iPod. Ejecting the disc appeared to cause a problem as there was no space left for the iPod to actually store any media. Also to note, there was no content on the FAT partition; just empty space.