back to work on my O2 sensor unknowns.........
Some of the sensors are wired a bit differently inside, something with the way the grounding works. Are you close to finding out?
yes i believe so. i need to scribble on the wiring diagram pages that i posted above, rescan them and let you check my work..........
here's my scribbling..............
the gist of the matter is the 2002 PCM used 7 connector pins to run it's O2 sensor system and the 1999 VCM used 9 connector pins to run it's O2 sensor system - the 2 pin difference relates to the low reference wires.
the 1999 system split the single low reference wire coming out of each of the 3 O2 sensor's connector into 2 (on the 1999 schematic above, splices : S151, S152, S153), and each wire got a separate pin at the VCM, for a total of 6 pins related to low reference.
the 2002 system tied the low reference wires for each of the 3 O2 sensors together (on the 2002 schematic above, splice S262). at this same splice 4 more wires were spliced in - 3 of these wires went to PCM pins related to an individual sensor. 1 wire went to a common low reference pin (C1-63), for a total of 4 pins related to low reference.
if I read the schematics correctly, on the 1999 wire harness, if I splice 1 of the 2 low reference wires from each O2 sensor together, and add 1 more wire to run to pin C1-63 on the 0411 PCM, then the spliced 1999 harness should be electrically the same as a 2002 harness.
whether or not the O2 sensors themselves and the harness sensor connectors need to be changed I do not know at this point.
this is why I have been contemplating taking all of the O2 sensor wiring out of a JY 2002 harness. I haven't yet peeled open the partial harness shown in the above pics to make a final decision........
little by little I'm gonna get it I swear