In this blog we go over what a Pin Drag Test is and why it's an important step in diagnosing wiring issues in your Subaru.
Why would I do a Pin Drag Test?
If you're noticing an intermittent connection between two plugs or getting weird check engine lights, it could be because the pins inside the plugs are not making a connection due to being loose or corroded. A lot of mechanics will use a multimeter to test for wiring issues, but this can be misleading since you could get continuity from a multimeter. The best practice is to also check for terminal resistance with a pin drag test in these cases.
Click here for more information on how to use a multimeter.
Did you know we have an iWire Multimeter?
What is a Pin Drag Test?
A Pin Drag Test (also called a terminal drag test or connector pin retention test) is a way to check the mechanical grip (retention force) of a female terminal on its corresponding male pin. In other words, you're testing how snugly the terminal holds onto the pin when connected. This helps you determine if the electrical issue is with the terminals, the housing itself, or another module in the car not working properly.
How to Perform a Pin Drag Test
- Disconnect the connector you're testing (for example, an ECU, sensor, or bulkhead connector).
- Use the correct male or female test pin or a calibrated test probe — never a random paperclip or thick wire, as it can damage the terminal. You can depin a terminal from the mating connector to get a spare terminal.
- Insert the test pin into each female terminal one at a time and feel for drag — a light but firm resistance as the pin slides in and out.
- Compare the “feel” across terminals:
- Normal: consistent resistance between pins.
- Loose: noticeably less drag or almost no friction → terminal tension is weak.
- Tight: unusually high resistance → possible corrosion or deformation.
What to do if a Pin Drag Test points to a Damaged Terminal?
You’re in luck! iWire has hundreds of Subaru-specific connectors, so you can either crimp on new terminals to the existing wire or, better yet, use our color-coordinated prewired pigtails so you know the terminals are crimped properly and make a good connection across the plug.
