There isn't a single, universally located "diagnostic test point" on a 2000 Ford Ranger like there might be on some other vehicles. Diagnostics are performed differently. Instead of a single test point, you'll use a scan tool (OBD-II scanner) to read trouble codes from the vehicle's onboard computer system.
The OBD-II port is your primary diagnostic access point. This is a standardized 16-pin connector, typically located under the dashboard, often near the steering column. This is where you'll plug in your scan tool to retrieve diagnostic trouble codes (DTCs) which will point you towards the problem.
