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Troubleshooting Trailer Wiring Connection for Lack of Brake Lights


My 2004 winnabago rialta came factory wired with a 6 pin round trailer connector. My boat and utility trailers have 4 way flat connectors. I bought a basic Hopkins 6 round to 4 flat adapter and got right and left directionals and running lights but no brake lights. I bought the Hopkins 47320 and got the same results. The led lights on the adapter worked for all lights except the brakes. An electric tester showed power to the rialta brake light pin but it does not connect to the trailer side of the hopkins adapters. Both trailers lights all work properly when connected to my GMC work van and Jeep wrangler 4 way flat connectors. I do not know why the adapters do not work properly.


Expert Reply:

The Hopkins Endurance Flex Trailer Connector Adapter w/ LED Circuit Tester - 6-Pole to 4-Pole # HM47320 and the other adapter you used most likely are not the issue. I recommend testing your 6-way connector with a circuit tester like # PTW2993 to ensure you have both brake and turn signal function on each of the lower pins.

If you have both the right turn and stop and the left turn and stop, then we know your vehicle connection is good. Since we know your trailer works with other vehicles, the only thing to cause the trailer and vehicle not to work together well isn't the adapter but rather a bad ground. Often a bad ground on a trailer will allow vehicle that produce more power through the trailer wires to still work even when the ground needs to be improved. I recommend checking the main ground connection on your trailer for a bare metal to metal connection free of rust or debris and then checking the trailer tail lights as they often have a separate ground sometimes through the mounting hardware.

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