This post was Last updated on : 07/22/2020
What is a starter relay & Why is it needed?
When we press starter switch, power flows from battery to starter motor.
Amount of power required to crank the engine is so high. For that, so much power need to be delivered from Battery.
That means high amount of current need to flow from battery to starter motor (Power = Voltage * Current. Voltage of battery is fixed 12v, so in order to deliver maximum power, current need to be high.)
For delivering high current, wire with a very high thickness is needed. That means a very high gauge wire have to travel all the way from battery to starter switch and then starter motor and back. To avoid this inconvenience & security risks we use a ‘Relay Switch’ in the circuit.
Relay works in some ways similar to a Transistor.
When we apply a small voltage to it, it turns on another closed circuit and deliver Power from Battery to Starter Motor. Thus avoiding use of long high gauge wire.
Why is Starter motor not Starting but clicking?
Finding the issue – why is starter relay ticking but self start not working? Let’s have a look at different parts of the system to figure out the problem.
But before that, here are some easily recognisable symptoms to find our problem easily
One tick sound from starter relay and then stops – either starter relay itself or starter motor is not working. Connect starter motor directly to battery if motor starts, most likely it is problem with relay. Replace it. If motor is not starting, there is some problem with motor(if battery is in good condition make sure it is good). Change Starter Motor carbon brushes and it will start working again.
Relay clicking continuously – Battery is low / dead. Replace it and try again.
Brake light not turning on when brake is pressed – There is a problem in the circuit. Read detailed troubleshooting part below to figure it out.
Nothing happens when starter switch is pressed – Need detailed step by step troubleshooting.For detailed step by step troubleshooting keep reading…
Detailed troubleshooting of starter relay / solenoid – Step by step.
Let’s have a look at different parts of the starter circuit to figure out the problem.
- Thick black wire from negative terminal directly connected to starter motor – This wire is connected to negative terminal of battery from the motor. Chance of this wire getting damaged is very very rare. But make sure the terminals are not corroded.
- Starter motor – Starter motors will stop working if carbon brushes inside becomes very thin. This part can be replaced with new carbon brushes(really cheap) for the motor. You can DIY or give it to someone else to replace it. Other than that there is very less chance of this part getting damaged. If it is damaged replace it.
- Ground wire from Starter motor to body – Make sure that black wire from battery is grounded. It would be connected to body of the bike, scoter/car. check weather it is done.
- Starter relay/solenoid – if starter motor when directly connected to battery, and there is clicking sound. Then you got a bad relay. It should be replaced.
- Starter switch – if there is nothing happens when starter switch is pressed, that means any of the 8 parts listed here is not working. Check all the parts starting from the battery, then brake lights, then starter switch(connect motor directly to battery), then relay and so on.
- Break switch for security – if light is not being turned on when pressing brake, that means there is some issue with this switch.
- Wire from Starter switch to relay – vely less chance of getting damaged. You can check for any problem in continuity using a multimeter.
- Battery – Last but least, Battery – People usually ignore this main part of the system. Make sure you got a fully charged battery. Most frustrating thing is, you might drain the battery while troubleshooting. So then even if you fixed the original problem, It won’t start. So be careful about that.