Trailer with a 4 Wire Connector that has 5 Wires

Published 06/18/2009

Question:

My 2007 Nissan Frontier has a 5-wire system, and a converter is installed making it a 4-prong 4-wire connection, and Ive tested it and it works fine. The trailer harness has a 4-prong connection, however there are 5-wires leading back to the trailer white ground plus 4 others, which makes it a 5-wire system?. I can only get the running lights connected, and occasionally if I play with the turn signal on the truck, the turn signals work properly. No brake lights or emergency flashers. Ive even disconnecting the converter and tried plugging the trailer connection directly into the 5-wire connection on the truck side of the converter. Any suggestions. Thanks.

asked by: Tom S

Expert Reply:

The reason you see 5 wires coming off the trailer connector on your trailer is that the running light circuit is split into two 'legs' right at the connector. One leg to run down the driver's side, one for the passenger. As far as the non-functioning lighting goes, the first step would be to use a circuit tester and test the 4-way connector on the truck. You've already done this, so the problem must exist on the trailer itself. Start at the trailer connector, examine it for corrosion or damage. Next, follow each circuit back, looking for loose connections, pinched wires, or wires with cracked or worn insulation. If you need a circuit teste, you can use one like # PTW2993.

expert reply by: Mike L