4-Pin Flat Trailer Light Circuit Tester

Check the lighting signals at a compatible four-pin flat trailer connection with a compact plug-in tester. LEDs provide a visible indication while the vehicle's functions are operated.

• ✅ Check at the connector - the tester plugs into a matching four-way flat arrangement.
• ✅ See separate signal indications - LEDs respond as the relevant functions are operated.
• ✅ Keep a small diagnostic accessory - the compact body fits with vehicle tools.

Check the Tow Connection Before Chasing a Fault

Use the tester with the vehicle secured and the connector correctly matched. Operate the lights and indicators as instructed, observing which signals appear at the test point.

An LED indication is not a complete load test or proof that all trailer wiring is sound. Confirm the US-style four-pin flat format; it does not directly replace European 7- or 13-pin testing equipment.

Technical details

• Connector: US-style 4-pin flat.
• Indicators: LEDs.
• Body: ABS plastic.
• Colour: black.
• Package: one tester.

Add a connector-level check to your trailer-light diagnosis.