Flow chart says to run the fan motor and check for a good connection between terminal #3 and the vehicle frame. The best way to do this is to check the:

• A. voltage drop between the two points
• B. continuity with an ohmmeter while energized
• C. voltage measurement at the supply
• D. resistance of the wiring between points

Answer: (A)

When a load is drawing current, any resistance in the return path shows up as a voltage difference between the load terminal and the frame. Checking the voltage drop between terminal #3 and the vehicle frame while the fan is running directly reveals the quality of that ground path: a small drop means the connection is solid, while a large drop indicates high resistance from a loose or corroded connection or damaged wiring.

This approach is more informative than measuring supply voltage, which only tells you the source is present but not whether the return path is good. It’s also more appropriate than trying to test continuity with an ohmmeter while energized, which is unsafe and doesn’t reflect how the circuit behaves under load. Measuring the resistance of the wiring without load similarly misses the impact of contact resistance that appears only when current flows.