Wiring an illuminated, marine-grade toggle switch requires extra effort and caution because the light emitting diode, or LED, is an added function not normally present on a standard switch. When wiring one of these, it's important to use switches and wires that are rated for marine use, that are more resistant to corrosion, and built to specifications that meet strict standards. Be sure to crimp all the connections because exposed solder quickly corrodes in marine environments. Finally, always use the switches to supply a negative (ground) circuit to the object they control.
Drill a 1/2-inch hole at the chosen location for the toggle switch. Mount the switch and tighten the retainer nut in place with a wrench.
Prepare a wire by using wire strippers and removing 1/2-inch of the wire's insulation. Cut 1-inch of heat-shrink tubing and slide it over the wire, then crimp a terminal onto the exposed copper. Slide the heat-shrink tubing back over the crimped terminal and apply heat with the propane torch. The tubing will shrink as the heat is applied, encapsulating the crimped terminal and wire connection.
Plug the prepared wire into the center prong of the switch. This will supply positive voltage so the LED will work. It is important that the switch is wired to a key-on voltage supply or it will stay illuminated all the time. Locate a voltage supply powered by the ignition switch that is on and off when the key is operated. Use a test light to determine the function. Tap into this voltage source, and prepare the wire connections following the approved procedure by using crimp connectors and heat-shrink tubing.
Prepare a new wire that includes an in-line fuse holder and connect it directly on the negative battery terminal. Insert a fuse in the holder that is rated for the object being wired. The amperage rating will normally be provided by the manufacturer. Route the wire to one of the outer prongs of the toggle switch. Be sure and follow the correct procedures for creating wire connections.
Prepare the last two wires and route one from the remaining switch connector to the object, and prepare and run the other from the object's positive voltage connection to the battery positive connection. After completing all of the connections, turn the key on and test the switch. The object will operate, however, the switch won't be visible during daylight.
