How to Find an Electrical Short on a Motorcycle

How to Find an Electrical Short on a Motorcycle

Motor cycle electrical system is known to confound the average local motorcycle electrical artisans and quite a few professional motorcycle mechanics.

Current motorcycle models are the ones with a more complicated electrical system as compared to a traditional wiring system.

Electrical problems are the main causes of the frequent visit to the motorcycle service center.

This is because likely every working part in current motorcycle models and controlled by an electronic component.

To ease troubleshooting, in any motorbike electrical fault, you need to simply understand every component with its functions, then troubleshoot independently and eliminate the source of the problem. The key factor is to understand the common causes of this problem and know where to start.


Before we think of troubleshooting, let us just recall some of the basics for a complete electrical system as we were taught back in school. An electrical circuit to be completed had to have three basic things.

These are; source of power, in this case, is a motorcycle battery, connection cables and the load such as motors, bulbs among others.

These are basic things that are used in proofing the flow of electrons in every circuit.

The absence or damage of one of these basic tools means that the circuit is not complete and no troubleshooting process will take place.

Another basic tool that you must not miss during the troubleshooting process is a digital multimeter.

This is a very important and accurate tool that can allow you to test an individual component and get instant results.

This tool is better as compared to test light since it is adjustable and can measure different fields starting from continuity to voltage variations and resistivity.

Electrical System Parts.

Before you think of initializing any troubleshooting process, my first suggestion is to get to know or familiarize yourself with your motorcycle electrical system.

First, you should know where each component is located.

You should be able to identify all individual electrical fuses, their capacity and also, you should download the circuit diagram from the manufacturer’s site and go through it, especially if you had not familiarized with the kind of electrical system.

Ensure that you fetch basic ideas on how the components are arranged, their location and functions.

Main Fuse.

How to Find an Electrical Short on a Motorcycle

The main source of frustration is when the main fuse is blown since this will kill the entire electrical system including the engine ignition.

The main fuse faulty can lead to poor engine performance if not complete shutdown.

It is quite frustrating since it will make you feel that there is a major engine problem or something unusual is happening in the entire system.

The causes of the fuse fault are when the fuse has been used for long without replacement, excessive flow of current or when it detaches for its socket due to regular vibration.

Keeping the spare fuse is very important since it can blow any time. The first step to diagnosing any faulty in motorbike electrical system is checking the main fuse.

The continuity of the main fuse can be done by making the respective adjustments to the digital multi-meter or by use of the test bulb.

Check Ground Wires.

The most common problem in motorbike electrical system is fault ground wires.

It is very difficult to track down the fault wires especially with a motor circle electrical system that has a lot of naked wires.

The problem symptoms that may be realized with these naked cables can be a completely dead bike or intermittent operations in some components.

Fixing these wires is not a major task, but it requires some patients.

All naked wires should be masked using electrical tape to avoid conducting the ground.

It is also important to check with the digital voltammeter if the individual wires are continuous with the ground wires.

Stator Checking.

In Motorbikes having a regular charging power problem, the owner must check the charging system. In this case, the charging system is the stator.

The stator provides extra power for battery charging during normal operations.

During the troubleshooting process, the stator must be disconnected from the plug that runs the engine, then tested if it produces the required voltage under normal resistance.

Check The Voltage Rectifier.

The voltage rectifier/ regulator is a portion that converts an AC voltage from the ignition coil to DC that can be used to charge the battery.

Its function is to ensure that the battery is charged to certain over the limit that may not be damaged. The regulator converts the excess energy into heat and gets rid of it.

Checking if the regulator is functioning well, is through the process of diode test.

The rectifier is disconnected from every other connection then the positive and negative terminals are identified. A multimeter is then set to diode function, then the positive terminal connected to the positive terminal of the rectifier.

The negative terminal also should be connected to its respective terminals, and in this case, you should expect no readings using a digital multimeter, or deviation if the multimeter is analog.

Secondly, connect in vice versa and expect the readings or deviation. If not so, the rectifier is faulty and it needs replacement.

Check Ignition Coils Plug Wires And Caps.

The ignition system is the most crucial part of a motorbike engine. it is where the all engine start is initialized and these parts must be properly taken care of to avoid any voltage leakage or any fault. The plug wires are thick cables running from the ignition coil to the plug cap.

You should check the plug wires if they are still intact, if not, replace with the new once, since the breakdown in wire insulation may lead to arcing in the plug wire that may lead to problems during engine start.

You should test the spark plug caps by adjusting your multimeter to the respective scale and read if its resistance is in thousands of Ohms.

Test The Source Coil.

The testing of the source coil is simply by checking its specifications using the shop manual, then the resistance should be taken from the output wires. The resistance should be around 300 to 500 Ohms.

Checking the CDI Coil.

CDI is a capacitor that stores, charges and discharges and electrical energy for engine induction.

This must be the last thing to be checked since it is automatically swapped by another CDI that is known to work, but not by just the use of a multimeter.

The motorcycle electrical system is simple for anyone who is patient and having the discipline of following simple instructions.

Anything that is said to be complicated, anybody can do it for themselves provided they are interested.