You can't determine what it means without having performed some form of diagnosis on the affected system.
For example an A320 apu starting circuit has a 400 ampere fuse. When this fuse blows the fault messages do not refer to it because the system is unable to determine where the loss of voltage occurred. The system often quotes the next relay in the chain as defective. So without the fuse its difficult to determine what was actually at fault.
These mesages are just a rough guide for maintenance as to where to look and also indicate that it isn't a good idea to use the mel based upon low intelligence fault messages
Last edited by Safety Concerns; 3rd July 2011 at 15:16.