Trailer Lights Not Working? Find the Problem Faster.

Stop guessing which wire or connection is causing the issue.

This easy-to-use 7-pin round trailer tester helps you quickly check the electrical connection between your vehicle and trailer, so you can see which lighting circuit may need attention.

Connect it. Test the circuit. Check the LEDs.

No cutting. No splicing. No complicated troubleshooting.

⚠️ Important — Check Compatibility Before Ordering

Designed for 12V ISO 1724 European-style 7-pin round connectors, including compatible setups in the USA, Canada, UK, and other markets.

It can be used with compatible:

• Cars
• Trucks
• Towing vehicles
• Utility trailers
• Caravans
• Campers
• Boat trailers
• Tractors
• Agricultural vehicles

Not compatible with US 7-way RV blade or SAE J560 connectors. Australian 7-pin round wiring may also differ.

Verify your connector type and wiring standard before ordering.

Have a US 7-Way RV Blade Connector?

We have a dedicated tester for that too!

Shop Our US 7-Way RV Blade Trailer Tester

Quickly Check Trailer Wiring Problems

A trailer light stops working.

Is the problem coming from the vehicle?

The trailer?

The plug?

The wiring?

Instead of checking everything one by one, this tester gives you a simple visual indication using LED lights.

It helps you quickly narrow down where the problem is coming from before you start replacing parts or tracing wires.

Plug In. Test. Know Where to Look.

1. Connect the Tester

Plug the tester into the compatible trailer plug or vehicle socket.

2. Press the Yellow Button

Activate the testing function.

3. Check the LEDs

The LED indicators help show which lighting circuits are responding correctly and which one may need attention.

That means less guessing and faster troubleshooting.

Check Common Trailer Lighting Circuits

Use the tester to help check:

• Left indicator
• Right indicator
• Brake lights
• Tail lights
• Rear lighting circuits
• Ground connection

A quick check before towing can help you catch a connection problem before hitting the road.

Test Both the Vehicle and Trailer Side

One of the biggest advantages of this tester is that it can help you determine which side of the connection may be causing the problem.

Check the Vehicle Socket

Connect the tester to your vehicle socket and activate the vehicle lights.

The LEDs help indicate whether the expected electrical signal is reaching the socket.

Check the Trailer Plug

Connect the trailer plug to the tester and use the powered test function.

This helps you check the trailer-side lighting circuits before spending time tracing wiring.

No Electrical Expertise Required

You don't need to be a mechanic or electrician.

The tester uses simple LED indicators to give you a quick visual reference.

If one circuit does not respond as expected, you immediately know which area to investigate first.

That can save time compared with manually checking every wire.

A Handy Tool Before Every Tow

Keep it in your:

• Vehicle toolbox
• Trailer
• Caravan
• Workshop
• Towing kit

Use it before a trip or whenever your trailer lights start behaving unexpectedly.

Compact, simple, and easy to keep nearby when you need it.

9V Battery Required

A standard 9V rectangular battery is required for the powered trailer-side testing function.

Battery is not included.

Why Trailer Owners Keep One Handy

Find Problems Faster

Quickly narrow down which circuit may be causing the issue.

Simple LED Indicators

Easy-to-read lights make troubleshooting much easier.

No Cutting or Splicing

Simply connect the tester and begin checking.

Check Both Sides

Helps you determine whether the issue may be coming from the vehicle or trailer.

Compact & Portable

Small enough to keep permanently in your towing toolbox.

What's Included?

• 1 × 7-Pin Round Trailer Plug & Socket Tester

9V battery not included.

Frequently Asked Questions

Does this work with all 7-pin trailer connectors?

No.

This tester is designed for the 7-pin round connector shown in the product photos.

Always compare your connector before ordering.

Does it work with the US 7-way RV blade connector?

No.

The common North American 7-way RV connector uses flat blade-style contacts.

This tester uses a different 7-pin round connection and will not plug directly into a standard 7-way blade socket.

Can it be used in Australia?

Yes, if your vehicle or trailer uses the compatible 7-pin round connector shown in the photos.

Australia uses several different trailer connector designs, so always visually compare your connector before ordering.

Can it be used in the United States or Canada?

Yes, on vehicles and trailers equipped with the compatible 7-pin round connector.

It is not designed for the common North American 7-way RV blade connector.

Can I test both my vehicle and trailer?

Yes.

The tester can help check both the vehicle-side socket and trailer-side plug, making it easier to determine which side may need attention.

Do I need a battery?

A standard 9V rectangular battery is required for the powered trailer-side testing function.

The battery is not included.

Will it tell me exactly what part is broken?

The tester helps identify which electrical circuit may have a problem.

You may still need to inspect the related bulb, fuse, wiring, plug, connector, or other component to find the exact cause.

Is it difficult to use?

No.

Connect the tester, activate the required function, and check the LED indicators.

It is designed to make basic trailer-light troubleshooting easier for everyday vehicle and trailer owners.

Stop Guessing Which Trailer Circuit Has a Problem

When your trailer lights aren't working properly, don't waste time checking every wire at random.

Connect the tester. Check the LEDs. Know where to start.

Before ordering, make sure your vehicle or trailer uses the same 7-pin ROUND connector shown in the product photos.