This from another thread :
DRIVEABILITY - ROUGH IDLE - DIAGNOSTIC TROUBLE CODES (DTCS) P0500, P0501, P0503, P1721, P0176, OR P1000 STORED IN MEMORY - WATER INTRUSION AT CONNECTOR C309 OR C340 UNDER DRIVER'S SEAT - VEHICLES PRODUCED BEFORE 1/2/2001
By this I would crawl under the truck in the area of the driver's seat and look up , inboard of the frame rail. There will be a square plug with a ~10mm bolt in the center.Remove the bolt and unplug the connector.Clean the terminals and coat with dielectric grease.
Only took me 1 minute using the SEARCH button.
Archimedes screwed us !
I knew a blonde dyslexic agnostic insomniac - she'd lay awake at night, wondering if there really was a Dog.
2003 Ranger Edge 3.0 manual 2WD