No Brake Lights or Turn Signals on Trailer With a 4-Way Connector With 5 Wires

Updated 09/07/2011 | Published 09/05/2011

Question:

I have a 4 pin, 5 wire plug. On trailer, Taillights ok, No brakes or blinkers. Theres white, green, yellow, green w/ brown, yellow w/ brown. Any ideas how to make all lights work? The car is a Honda crv, but didnt work w/ jeep liberty either.

asked by: Kevin

Expert Reply:

You will first want to make sure the 5 wires on the trailer plug is wired properly to the trailer. The white wire is for ground, the green wire for right turn and brake, yellow wire for left turn and brake, green with brown wire is for right side running lights, yellow with brown wire is for left side running lights.

If the wiring is all correct then you will need to check the trailer connector on the truck and trailer for a ground connection issue, or a short on the tail light circuit on the trailer. Open them up and make sure there is no white or green corrosion causing an issue inside the connectors. If so clean them out or replace the connectors with new ones.

If the problem is not found in the connectors, you will need to follow the trailer wiring and check all of the grounds for all of the lights and the trailer connector. Make sure each light is grounded to the trailer frame and that the connection to the trailer frame is free of rust, paint and corrosion. Other lights like running lights down the side of the trailer may have a separate ground wire or they may be grounded through the mounting hardware so you will need to check each of these lights.

While you are checking all of the ground connections, it is a good idea to look at all of the wiring and check for pinched cut or frayed wires that could be causing your issue, or could cause an issue in the future. I am including a link to a troubleshooting video that should help you with locating the problem on your trailer.

expert reply by: Jeff D