How to Wire Marker Lightsby Andrew Hazleton
Side marker lights are required on any vehicle driven or being towed on highways. Check with your state rules, but most states require red marker lights on both tail lights, and amber marker lights mounted near the front of the vehicle. Marker lights must be visible from each side of the vehicle.
Wiring marker lights to either your vehicle or trailer is not complicated and can be performed with a minimum of tools and expertise.
Identify the appropriate power wire for marker lights. On a vehicle, this will be the wire supplying the parking lights or rear tail lights. For trailers using the standard four-wire scheme, the orange or brown wire will be the correct source for marker lights.
Examine the marker light, and determine the "hot" wire. This will be any color but black, but most commonly white.
If there is only one wire, this is the "hot" wire.
Using a splice connector, attach the hot wire to the power wire identified in Step 1. A splice connector allows you to splice a wire to another wire without the need to make any cuts. See the Resources for a sample splice connector.
Connect the black wire to ground. If your vehicle has a ground wire easily available, you can connect to that. Most trailers do not have a ground wire, but rely on the chassis of the vehicle to serve as ground.
The ground wire can be connected to the chassis by a screw, clip or any other means to assure electrical contact. Use sandpaper to expose bare metal to assure good connectivity.
Verify the marker lights are illuminated at the same time as the vehicle tail lights.
- Some marker lights may have only one wire, and rely on the mounting screws to make the ground connection.
- If your trailer is exposed to salt water, consider sealing the ground screw contact with epoxy to avoid corrosion.