Your first instinct may be to replace the headlight on your motorcycle if it malfunctions, but this may not be the best course of action. Problems with motorcycle headlights can be caused by a range of issues, including faulty wiring, bulbs and connectors. Troubleshoot a motorcycle headlight in order to narrow down the possible cause of the headlight malfunction.
Start by removing the headlight. At the back of the headlight, you will see a plug. Follow the wire that connects to the plug. As it makes it way to the wiring loom, look for any broken or exposed pieces of wire.
Examine the plastic pieces around the headlight plug and bulb. If you find the plastic is burnt, or the contacts are dirty, replace the damaged parts.
Look for blown fuses or damage to the bulb. These items will cause power failure to the motorcycle headlight.
Check the wattage of the bulb that you have in place. Look at your manufacturer's guidelines to make sure the bulb wattage of the motorcycle headlight is the correct type for your bike. The wattage will be listed on the rear of the motorcycle headlight.
Test the relay of the motorcycle headlight. If the headlight does not always turn on with the bike, it could be a problem with the relay. To troubleshoot the motorcycle headlight in this case, you would remove the relay, and replace with a known working relay.
Receive a voltage reading on your motorcycle's battery. If you find that fuses blow frequently on the headlight, or the headlight dims frequently, check the battery voltage with a voltage meter. Readings should normally be in the 12-13 volts range.