Troubleshooting Trailer Brake Lights not Working after 4-way Install on a 1998 Nissan Frontier

Question:

Installed t connector on 1998 Nissan frontier have everything but brake lights

asked by: John

Expert Reply:

The first thing I would do is test the circuits of the 4-way on the Tow Ready Wiring Harness part # 118362 with a circuit tester like part # PTW2993. This will tell you if the problem is on the vehicle or the trailer. To see how this would be done check out the video link I attached.

If the voltage is there like its supposed to be then you know the problem is on the trailer wiring. The first place to check is the grounds of the light assemblies. A weak ground can cause taillights not to function correctly. You will want to make sure the ground wire is attached to a clean metal surface, or if the assemblies ground through the mounting assemblies that they are installed on a clean, rust-free metal surface.

If there isn't voltage at the 4-way then the problem could be that the connectors of the harness are not completely seated where they attach to your vehicle wiring or the ground you chose for the harness is not sufficient enough.

I also attached an FAQ article on troubleshooting 4-way installs as well as an FAQ article on trailer wiring.

expert reply by: Jameson C