Troubleshooting Camper Lights When Both Turn Signals Blink At The Same Time

Question:

On our camper, the turn signals, brake lights, and parking lights all work individually. But if you turn headlights on or brake lights along with turn signal, both turn signals blink at same time. Also, marker lights dont work at all.

asked by: Wayne P

Expert Reply:

It sounds like you have some wiring issues that may be on the trailer. Many times, there is a bad ground connection somewhere. You will want to make sure the trailer connector ground and the ground for all of the lights are connected to clean bare metal surfaces. Weak grounds can allow some functions to work individually but may not let multiple functions work at the same time. You can also make sure that the vehicle side and trailer side connectors are clean and free of any corrosion.

If you have a 4-way connector but it has 5 wires coming out of the back of the connector, then this is a wishbone harness, and it will have the running light circuit split at the trailer connector. One wire goes to the left running lights and the other to the right running lights. If this is not wired correctly you can have problems.

You can have someone get behind the wheel while you test the pins on the connector with a circuit tester like part # PTW2993 to make sure the vehicle harness is properly installed. If you find there is power on both turn signal pins at the same time, then the problem is with the vehicle wiring or tow package wiring.

I have attached a helpful article that explains trailer wiring and shows how the wires should be run.

We would need to know the year, make, and model of your vehicle to make some recommendations.

expert reply by: Jeffrey L