Thanks for the responses guys.
I've managed to narrow down the search though - it's in the harness somewhere south of C3001 - the large black plastic connector mounted on the driver side strut tower - but it's north of C120 - one of the connectors on rear passenger side valve cover, near the strut tower. So it's somewhere in the harness that connects the EVR solenoid / PCM / MAF / VSS / C645 (tranny hardware unit). Which runs behind/below the engine
The only splices on this part of the harness are S59, and S178, but for some reason the service manuals (while giving location diagrams for every component and connector) don't give a location for the splices beyond the text description I quoted. I'm guessing S59 isn't too far from the C3001 connector, since the MAF power comes off that splice, and I suspect S178 is down low to the rear, since the VSS and hardware tranny unit power come off that one.
At least knowing it's north of C120 means I don't have to pull the UIM and look at the injector harness.
I have pulled the PCM connector, and the short to ground remains. I disconnect C3001 and the short goes away, so it's south of C3001. I pull C120, and it remains, so it's north of C120. I was thinking it'd be best to start by looking at the splices, but I may have to just start at C3001 and inspect it all the way. But that "behind/below the engine" is going to be a PITA. I will need to move it off the street if I have to jack her up to examine anything from underneath.
So far the schematic diagrams seems correct as to wire colors matching pin numbers, but they did reverse the relay pin numbers 3 and 5 on the schematic. BTW, I have the actual paper copy of the 98 EVTM, and I'm comparing it to a 97 service CD.
