well i finally got my factory manual today, which would have saved some time. some notes...
4doorciv: the plug is for the light relay.
cam: it is not, i looked. the 4d55 has a different harness for some major elements. since the alternator is on the passenger side of the truck the fusible link is on that side of the truck to protect things. odd location.
i will have to send you some diagrams at some point cam to flesh out the online diesel info.
tom