Checking your lights should be part of your preflight check every time you hook up the trailer. When you find a light is not in working order, it’s usually a simple to troubleshoot the problem.

If a single light is not working, start at that light and work your way back. Open the lens and remove the bulb to inspect the filament. Some trailer lenses have external screws. Some lenses fit into the body of the trailer, requiring you to loosen the lense from the inside and pop it out.

Your trailer likely uses a standard tail light bulb. Single filament bulbs (1156) are used for turn signals. Dual filament bulbs (1157) are used for running and brake lights. Holding the bulb up, a broken filament is usually self-evident. Replace the bulb with a known good bulb and try the light again before you reassemble the lens.

If replacing the bulb did not solve your problem, begin checking at the plug that runs from your bike. Let’s say your left turn signal is not working. Attach a test light or voltmeter to the pin on the bike-side plug that should be the left turn signal. Activate the signal and check the meter or light. If the voltmeter needle shows no activity or the test light does not blink, the problem is likely on the bike and not in the trailer.

If the voltmeter needle swings or test light blinks, move to the trailer and check for any breaks in the wire between the trailer plug and the turn signal socket. If this wire run shows continuity, check for continuity between the ground side of the light socket and the ground wire on the trailer.  Unless the trailer has sustained damage to the wiring harness underneath, the best candidates for problems are a loose ground wire or a problem at the plug.