Using 6-Way Round to 7-Way Adapter and Trailer Lights Flash when Brake Pedal is Released

Question:

My motor home has the 6 pin round connector and my trailer is 7 pin blade. I bought the adaptor and had to do some retiring and know I have running lights, left and right turn signals and the brake lights just flash when I let off the brake peddle. My motor home has the red brake lights and the amber turn lights. What can I do? Could this be the problem?

asked by: Dan W

Expert Reply:

On a 6-Way round trailer connector the brake lights and turn signals should already be combined on the same circuit, one for each side of the trailer. So it would not matter if the RV had separate turn signals and brake lights. That is unless someone wired one in and didn't know that trailers use combined brake lights and turn signals. Also, if the hazards are turned on then the brake/turn signals on the trailer will just flash.

Use a circuit tester such as # PTW2993 to test the functions of the 6-Way round connector without the adapter or trailer connected. They should match the picture I have included. If they do not and you have one pin for right turn, one pin for left turn and one or no pin for brake lights then you will need to use a converter such as # 119178KIT.

The converter will take the separate circuits and combine them. Then you would cut off the 4-Way on the converter and wire it up to the 6-Way round to match the picture I have included. Then the adapter # 47435 should work just fine.

You might also want to make sure the grounds on the trailer are good. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.