Motorcycle Tech Tips

Tracking Down Those Electrical Gremlins

Unfortunately with any vehicle, even if it is properly maintained, there are sometimes electrical problems. A lot of the time, age affects different parts of the motorcycle. It especially affects the wiring of a motorcycle. Custom motorcycles or shoddy workmanship can also lead to a lot of electrical woes. Some problems can be easy to fix, but on today’s complex motorcycles some of these electrical issues can be difficult to track down.

Two essential tools that are a must have in any electrical tool box are a test light and multi-meter. Remember, working on a motorcycle is not like working on a house’s electrics. There are only 12 volts with low amps. 12 volts could barely be felt from a motorcycle battery if both terminals were crossed, but there are parts of a motorcycle that intensify electricity such as an ignition coil. These can give a dangerous jolt and caution must be exercised working on these. Caution should be used when working with any electrical part, because though it may not be able to harm you, it can still start a fire.

Electrical systems work with a positive side and a ground side (negative side). The negative side is usually attached to the frame of the bike creating a surface to ground other compo¬nents. A wire connected to the positive side of the battery but not grounded will have no effect. A light will go on once it is grounded. A switch breaks the ground to turn a light off and create an open circuit. Wires that are improperly grounded or creating an open circuit are usually what cause electrical problems. Wires that have damaged insulation or a break can ground out when they should not. A fuse box or circuit breaker system is designed to break the circuit in a case of a faulty wire so that it does not start a fire. These are always a good place to look when electrical problems exist.

A test light is a great tool because it is basically a light with a wire. The probe is the power source and the other end of the tool is grounded. When the light goes on, that means there is a source of power detected. This is very useful when locating a break in a wire. Probing along the circuit will show where the power stops and where the break is. Sometimes when a wire is hidden within the frame this can be tricky. A multi-meter is a helpful tool with this. This tool has multi functions, such as checking voltage, reading amperage in DC and AC and checking for continuity. Continuity will tell if there is a break in the circuit. If both ends of the wire read no continuity, it means the wire has a break. This can be used to check if light bulbs are good or if a switch is good.


A parasitic draw can kill a battery when the bike is off. Sometimes what causes this is unknown. Using a multi-meter can detect how much of a draw there actually is. The multi-meter is used in-between two parts of the circuit. Usually a draw is measured from the negative terminal of the battery to the negative wire to the frame. There should be very little draw when the bike is off - if there is not, it is a parasitic draw. Pulling fuses until the draw completely drops will help determine where it is coming from. If there are no fuses, wires may have to be disconnected until the draw goes away. Often times the charging system or ignition system is a good place to start.

Multi-meters also contain voltmeters. These can determine if the charging system of a bike is working or if the battery is in good charging condition. With a lot of new bikes a computer runs a lot of the electrics. Diagnosing problems on some of these bikes may take special tools or scanners. Researching conditions is a great way to help find where to start. If all else fails, a dealer or certified repair shop can usually diagnose the issue. Be careful around electrical work as it can lead to harm or fire if done incorrectly. With a little patience and some basic know-how, most electrical gremlins can be found.