Diagnosing a bad FireWire port

Jun 11, '03 10:57:00AM

Contributed by: barryjaylevine

I had an issue with my Dual-867; FireWire devices would intermittently drop off the bus. Symptoms included Toast going off into NeverNever land when launching or when clicking the "Eject" button after a burn (after coming back to my Mac from a 30 minute break during which time the burn was taking place). Another symptom was the Mac telling me that I had disconnected a FW drive (when I had not). Sometimes the problem manifested itself within the first two minutes of use; other times after 40 minutes. It first happened after the 10.2.6 update so I reinstalled the Combo updater (no improvement), and then did a clean install on another drive with 10.2.4 (same problems). Booting into single-user mode, I found the following message appearing (all on one line):

IOFireWireSBP2Login::fetchAgentWriteComplete fetch
  agent write failed! retrying
It would repeat five or six times, then pause about a minute, and then repeat again, etc. Sometimes it would appear within the first minute after boot and other times it would take 30-40 minutes until it would appear - the same frequency the problems would develop when booted to the Finder. Suspecting a bad FW port (the lower port on the motherboard), I swapped the FW devices to the upper port...and the problem disappeared.

Bottom line: Bad FireWire port. Still under warranty, I brought the unit into CompUSA. The Apple technician could not find the problem using whatever standard procedures Apple has developed. (Most burns to a FW device will succeed.) However, when I provided a photo of the screen showing the "IOFireWireSBP2Login...etc." and explained how I diagnosed the problem, the tech agreed that the motherboard would need to be replaced. So, if you have this problem, take a picture of the screen to document it and don't be too hard on the tech because this kind of a problem is apparently not documented very well for them.

PS - I'm buying AppleCare before the warranty is up!

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