Troubleshooting Trailer That Doesnt Have Turn Signals, Brake Light, Or Running Light On Left Side

Question:

The lights on the right side of my trailer works,except running lights,flashers,brakes works fine,left side nothing at all,could you give my some advice on how to correct this

asked by: Joseph W

Expert Reply:

Since the lights on the left side of your trailer are not working, I recommend checking that the 9 o'clock pin if you have a 7-way connector, or the pin with a yellow wire of a 4-way connector has power by using a circuit tester like # PTW2993 when the turn signals and brakes are applied on your 2003 Ford F-150.

Both of these pins control the brake lights and turn signals for the left side of the trailer as they share the same circuit.

If you have no power to this pin, then I recommend checking that the fuse for the left turn signal and brake is not blown or missing from the engine bay fuse box.

It is a little odd that the running lights are not working either, as they are on a completely different circuit than the turn signal and brake lights, so I would check that the ground wire on the left side lights are connected to clean corrosion free metal, and that the main ground on the tongue of the trailer is also securely connected.

I included a link to a helpful article on wiring for you to take a look at.

expert reply by: Samuel C