Loose electrical connections are a source of many erratic and intermittent driveability problems. Female terminals can become loose from vibration and stress on the connector. The pin drag test is used to identify loose connection that can cause these intermittent problems.
Always begin by visually inspecting the male and female connection for damage or corrosion. If no damage is found insert a matching male terminal into the female side of the connection to feel tension in the terminal. You can use a terminal from discarded connectors or purchase pin drag test terminal assortment kits for this purpose. The female terminal should provide a firm fit on the male test pin. Use a small pick to gently tighten any connectors that feel loose.