Typical Trailer Tail Light Wiring

These are the typical tail light wiring colors found on trailers.

Semi-trailers and European caravans have separate turn and stop lamps and "Everything Else" is usually wired for shared turn/stop lamps.

Dual filament bulbs may be used to provide both tail and turn/stop functions in a single bulb, but they are wired like two separate light bulbs.

Base of single filament "1156" bulb on left, dual filament "1157" bulb on right.

7-Way Round Pin J560 Variations

The 7-Way Round Pin J560 connector has two common wiring variations, depending on application.

The semi-trailer variation has separate stop lamps and no provisions for electric brakes.

The "Everything Else" variation can be used with electric brakes and uses shared stop/turn bulbs.

When working with 5th wheel, gooseneck or tag trailers that have a 7-Way Round Pin plug, you need to verify if they have shared or separate turn and stop lamps.