7-Blade & 4-Pin Trailer Plug Tester – LED Tow Vehicle Wiring Tester
This tester checks both 7-way RV blade connectors and 4-flat trailer plugs to confirm that power is reaching the trailer connector on your tow vehicle. It quickly verifies that the vehicle wiring and trailer fuse circuits are functioning before you connect your trailer.
Modern trucks often use dedicated fuse circuits for trailer wiring. When a fuse blows or wiring fails, the issue is not always obvious. This tester confirms that power is present at the plug so you can identify wiring problems before hitting the road.
How It Works
- Plug the tester into your tow vehicle’s trailer connector
- Operate the vehicle’s turn signals, running lights, and brake lights
- Green LED indicators illuminate when power is present on the circuit
Need help identifying trailer wire colors? Click here for a wiring reference guide.
Features
- Tests both 7-blade RV connectors and 4-flat trailer plugs
- LED indicators confirm power on each circuit
- Quick diagnostic tool for tow vehicle wiring
- Helps identify blown fuses or wiring faults
- Simple plug-in design – no tools required
R&P Knowledge Hub
Trailer wiring problems are commonly caused by blown vehicle fuse circuits, damaged connectors, or corroded trailer plugs. Testing the tow vehicle connector before connecting the trailer helps isolate whether the problem is in the vehicle wiring or the trailer wiring.
Wire colors are not always reliable across different trailer manufacturers, so electrical testing should always be used to confirm the function of each circuit.
Verify wiring functions before connecting your trailer.
