Let’s start here; trailer wiring can be confusing. Nothing is the same except you tow the trailer. Let’s talk about the differences in the 2 lighting types.
Aka 4 wire.
This is where your turn signals and brake lights are combined on the same wire and bulb.
Aka 5 (or more) wire.
This is where your turn signals and brake lights are different wire and bulbs.
If you look at the picture above, you can see the light on the left has no separate turn signal as compared to the other light. As styling evolves (especially with the use of LEDs), it might be harder to visually determine if your tow vehicle is an import or domestic type.
On your trailer, it’s usually pretty simple to determine the type. Count the number of terminals on your plug. If you have 4 connectors, it’s a pretty safe bet you have domestic type wiring. If you have 5 (or more), you are probably import. The extra wire could be anything from an interior light to brakes (usually only on a camper).
HEY! This is really important. There is no ‘industry standard’ for trailer wiring in the Powersports Industry. Be sure you compare wire function and not just wire color.
Here is a handy chart to tell you what you are going to need based on the tow vehicle and trailer.
|TOW VEHICLE ↓
|2 to 3 Converter
|5 to 4 Converter
|HD CanBus module
*starting in 2014, Harley switched to a CanBus controlled lighting system. All bikes except the CVO Limited (2014/15) and Road King (all) require our Harley CanBus module. See our application chart for the most current info.
This material © Electrical Connection. Print authorization is granted for standard and digital media when credit is given to the author to include the website.