Alright, so I haven't been able to actually fix my truck yet. That badly corroded wire is not involved with the VSS at all. According to the electrical diagrams, the wires going to the VSS are Red/pink and Light Green/Black, just like you said. The badly corroded wire is a looked like a dark blue one, but there was grime all over it, and it's pretty difficult to tell. I cleaned a lot of the corrosion off, and there wasn't really any wire left in that one spot where the insulation was open. I then took the truck for a little spin just to see if it was the VSS wire (this was before I looked up the wire colors). The speedometer worked and it shifted fine, so I figure that's not it. I think it's for my right side trailer brake/signal bulbs, but that's just a wild guess.

I haven't really made time for serious troubleshooting, I just thought I'd give you guys an update.

 

Okay, so the VSS wires appear to be intact where the harness is torn apart there. The problem must be elsewhere.

I guess I'll check out the connections first, and then start tearing into the harness trying to find out where the wire(s) is damaged. I'll go ahead and raise this question now. What if I don't find anything?

Another question is, is it worth it to ohm the wires, since my problem only happens very occasionally? The ohm test would only yield useful results when the circuit is malfunctioning, correct?

 

Did you ever figure your vss speed sensor out?