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.
