What is the purpose of testing points on a wiring diagram during troubleshooting?

• A. To verify wiring against the actual vehicle by measuring voltages or continuity at specified test points.
• B. To determine service intervals for components.
• C. To identify the color of every wire in the harness.
• D. To locate the vehicle's entertainment system.

Answer: (A)

Testing points on a wiring diagram give you reference locations to compare against the actual vehicle wiring. By measuring voltages or continuity at these points, you verify that power, ground, and signal paths match the diagram. This lets you confirm that the circuit is correct and identify exactly where a fault lies—open circuits, shorts, or bad connections—so you can isolate and repair efficiently. The other options don’t fit because service intervals aren’t determined from test-point measurements, wire color alone isn’t a diagnostic check, and locating an entertainment system isn’t part of wiring troubleshooting.