How to Troubleshoot Lights on a Boat
Few things are more frustrating than switching on a light and having it not turn on. In a boat, such an occurrence can leave you sitting in the dark, or worse. Worse is needing to operate the boat in the dark without the required navigation lights. Such unlit boats are safety hazards to yourself and other boaters. You can also be subject to heavy fines if spotted in an unlit boat, after dark, by an enforcement patrol.
Other People Are Reading
Instructions
-
Check the Obvious
-
1
Activate the light switch several times. It may have not been switched all the way on or perhaps there was an internal malfunction which self corrects. If this is the case, leave the lights on for now, then recheck the switch at a later time. "Don't fix what isn't broken" is a poor mantra for boaters.
-
2
Check the fuse. Some boats have a fuse panel, while other systems rely on in-line fuses. Most "blown" fuses can be detected visually, but to be sure, insert a new fuse and see if that corrects the problem.
-
-
3
Check the light bulb or bulbs. A burned out bulb is often visually apparent but change the bulb anyway, then recheck.
-
4
Check the contacts on the light socket for corrosion. If present, position the light switch to the off position, scrape off the corrosion in the socket and then retest. Marine environments, especially salt water, are very corrosive.
Dig Deeper
-
5
Pull out your 12V test light and prepare to dig into the wiring of the boat if the bulbs and fuses are replaced and the switch still fails to turn on the lights. The light switch will be your initial suspect.
-
6
Access the rear of the light switch where the wires connect.
-
7
Ground the clip at the end of the test light to the negative post on the battery, if possible, or to some other metallic ground.
-
8
Touch the "power in" post or connection on the back of the switch with the probe on the test light. If not marked, or if it's impossible to trace the wires to the back of the switch, touch each connection with the probe. One should be constantly hot from the battery. If touching the power-in connection lights up the tester, you know the fuse and wire from the battery are OK.
-
9
Touch the other posts or connections on the back of the switch and turn the switch on and off. If the test light glows when the switch is on, the switch is good.
-
10
Move to the malfunctioning light. Ground the test light. With the light switched on, carefully touch the positive or power-in connection in the bulb socket where the base of the light bulb would touch. If power from the switch isn't getting there, inspect the wire between the light fixture and switch, paying particular attention to solderless connectors or other connections where the wires are tied together. Again, suspect corrosion.
-
11
Suspect the ground wire if testing shows the power does get all the way to the light fixture.
-
12
Trace the ground wire back to where it connects with the battery or fuse panel. Again, suspect corrosion with connections where wires are joined.
-
1
Tips & Warnings
Having spare lightbulbs, fuses and a small tool kit including a 12V test light stowed in a storage compartment or in a waterproof tool box inside the boat at all times is a great idea.
