A starter relay is a small electronic component that controls two circuits—one for low current, and one for high current—in an electric starting system. These circuits work together to trigger the starter motor and solenoid, which then crank the engine.
Starter Relay Installation and Wiring
A starting system consists of an ignition switch and relay, a solenoid and a starter motor, and a few other parts. The ignition switch controls the low-current circuit, and the relay relays the high-current circuit to the solenoid and the starter motor.
The solenoid engages a plunger, which, in turn, pushes a disc against a set of contacts. Once those contacts are connected, current can travel from the battery to the starter motor to crank the engine.
Depending on the make and model of your vehicle, the exact location of your starter relay varies, but it is usually under the hood or behind a side panel. Typically, it is a small box with three or four metal terminals. It may also have a fuse inside and be held on by bolts that secure it to the body of the vehicle.
You can wire a starter relay to your scooter using a variety of tools and a little technical know-how. It requires nothing more than a pair of pliers, some wires and an understanding of how the relay works.
Step 1: Locate your starter relay and inspect it for signs of damage or a poor connection. If the relay looks fine, skip to step 2.
Next, connect a thin pair of wires from the ignition switch circuit to the smaller metal stud terminals on your starter relay. The wires should be of the right gauge to carry low current from the ignition circuit to the coil winding of your relay.
Check the connections for continuity
Next hook a Continuity Tester up to the wires that you just connected and make sure that the meter reads “B” for the relay battery and “M” for the starter motor terminal. When the meter shows that continuity exists, you have successfully wired the starter relay.
If the meter reads no continuity, you have probably wired it incorrectly and need to do some further troubleshooting. You might also want to swap out the fuse in your starter relay for another of similar size and rating.
A few common reasons that a starter relay goes bad include broken leads, lack of conductivity, overheating or a poor circuit in the bike, and general wear and tear from exposure to heat, dirt and debris, or corrosion from riding or storage conditions.
Regardless of the cause, your starter relay will need replacement as soon as it fails to function. If you don’t have the necessary tools or space to do it yourself, there are local bike shops that can do the testing for you.
The most important thing to remember when wiring a starter relay to your scooter is to test the system before you replace it. That way, you’ll be able to identify whether the problem is the relay or a component in your wiring system.