Welcome to The Ranger Station!
I will send you schematics for 2000 Ranger (or 1993 Ranger) if you send me your email address in a Private Message. I will actually send you a LOT more schematics that you probably need, much of the EVTM.
This offer is open to anyone who sends me a PM for 2000 or 1993 EVTM schematics. I have a lot less of the 93 schematics saved, but still have both books (paper) and will take photos of schematics, if needed. If you PM me and DON'T include your email address, well....I can't send them, now can I? It's surprising how many times I get that.
Since replying to your post, I looked up C309.
It's under the driver seat, toward the transmission.
Quite a bit goes through that plug.
It would be quicker and easier if you would describe the problem, tell us which circuit, give wire colors, etc., so that I can go into that particular schematic. That plug tends to get corroded.