Cargo vans and box trucks can lack adequate interior lighting, and installing extra lights can be as simple as adding to the existing system or as complex as creating an independently switched system. The average backyard mechanic can install dome lighting in about 30 minutes.
Decide on an adequate amount of light. Four 12-volt dome lights can easily provide enough light to load the van at night. Four bulbs also do not cause excessive draw on the van's electrical system, so the lights can be left on after the van's engine is shut off.
Decide on placement. Good places for extra light are normally up high on the ceiling or at the rear deck where they shine on the ground outside. Most times, aligning them along the upper body panels is easier as there may already be holes for running wiring.
Disconnect the battery from the van.
Run the wires from the battery or fuse panel, or from an existing light in the cargo area, to the rear lighting locations. It can be buried in the panels or simply taped into place. Do not connect the wires to the battery at this time. The red wire is usually positive and the black is negative, unless RV lighting is used, in which case the black is positive and white is negative.
Strip the wires about an inch down from the end and splice them into the new lights. The lights can be held up temporarily with string or tape, or the splicing can be done on the floor and the lights raised into position.
Install the lights. Most types will have sinker screws with a Phillips-head pattern. These will drive into most metal, and should not be used on the roof or sheet metal of the van. They are only for use on the body frame rails, which are typically exposed in cargo vans. Mounts can be added to the rails and the light mounted to the flat adapter. This prevents screws from puncturing the sheet metal. Small, lightweight lamps can be held up with a strong adhesive glue.
Connect the wires to the correct terminals on the battery or fuse panel.
