Starter Solenoid Wiring Diagram: 3 Pole Starter Diagram

Starter Solenoid Wiring Diagram

A starter solenoid is an electromagnetic switch that connects and disconnects the battery to the starter motor assembly. It is a huge switch, which works as a bigger relay to turn ON and OFF the starter motor assembly.

The starter solenoid works on the principle of electromagnetism. It has three terminals on the back of the solenoid cap.

If you want to know the starter solenoid wiring diagram in simple words. This page explains very easily. On this powerful page, you will learn the starter solenoid wiring, especially the 3 pole starter solenoid wiring diagram in understandable language, so that you know what wires go to the starter solenoid.

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The Starter (Engine)

Starter Solenoid and Motor Assembly
Starter Solenoid and Motor Assembly

Many people get confused between the starter motor and the starter solenoid. A starter consists of two components, a starter motor assembly, and a solenoid. A starter motor assembly is the bigger cylindrical component used to crank the engine.

While a starter solenoid is a small cylindrical component, placed on the top of the starter motor assembly, which makes and breaks the connection between the starter motor assembly and the battery.

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What is Starter Solenoid in A Car

A starter solenoid in an automobile is a type of electromagnetically actuated switch which enables the engine to start by providing an electric current to the starter motor. It consists of two main components, an electromagnet, which is activated when a current passes through it, and a plunger which completes the circuit by engaging with the starter motor.

Starter Motor Pieces

The starter motor is an essential part of any internal combustion engine. It consists of several components, including a commutator, brushes, pinion gear, lever fork, overrunning clutch, field coil and armature, and planetary gear set. The armature is the cylindrical component that creates an electromagnetic field in response to the current from the ignition switch. The commutator connects the current from the brushes to the armature windings.

The brushes ride on the commutator provide the current for the armature to create a strong electromagnetic field. The starter’s pinion gear, overrunning clutch, and planetary gear set are connected to one end of the armature shaft. The field coil or permanent magnet interacts with the armature to produce a rotational force. Finally, the starter motor is completed by a solenoid, which is a small cylinder bolted on top of the starter motor assembly and serves as a switch to turn it on and off the starter motor.

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Get to Know How Automobiles Start Up

The car starting system works by converting electrical energy from the car battery into mechanical energy. This energy is used to initiate the first working cycle of an internal combustion engine by activating the starter motor. When you turn the ignition key to the “start position”, the current flows from the ignition switch to the starter fuse and then to the starter safety switch.

Depending on the type of transmission, the safety switch may be located at the clutch pedal end or at the gear shift lever. When the safety switch is activated, this leads to control the starter solenoid by flowing current through one of the terminal of the solenoid which pulls the starter’s plunger and causes the armature to spin which leads to turn the pinion gear, as a result, the starter motor draws a large amount of current from the battery.

The solenoid acts as a bigger relay and energizes the starter motor assembly, which consists of an armature, commutator, brushes, pinion gear, overrunning clutch, and planetary gear set. When the armature starts to rotate, the pinion gear is pushed forward by the solenoid to mesh with the engine flywheel, thus the starter motor turns the flywheel and allowing it to start. Once the engine starts, the flywheel speed increases, and the one-way clutch disconnects the starter motor armature from the engine’s flywheel ring gear to protect it from overspeeding and burnout.

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Starter Solenoid Wiring Diagram

Starter Solenoid Wiring
Starter Solenoid Wiring

The starter solenoid wiring diagram is very easy, don’t worry. I am here to explain it quickly. A starter solenoid has three terminals, one small pin-type terminal, and two thicker bolt-type terminals.

Car Starter Motor Control Circuit Diagram
Car Starter Motor Control Circuit Diagram

The small pin-type terminal is called the “S” terminal. The “S” terminal links with the ignition switch circuit. This circuit is called the starter solenoid control wire, which links the ignition wire to the starter solenoid. The ignition switch sends the current to the starter solenoid through the fuse, then to the neutral safety switch, then to the starter relay, and finally to the starter solenoid.

The starter solenoid’s one thicker terminal is the input terminal means the battery’s positive power source enters the solenoid through this terminal, and the second thicker terminal is the output terminal, which goes to the starter motor assembly.

When you turn the ignition switch key, the current starts to flow from the ignition switch to the starter fuse, then to the neutral safety or clutch pedal safety switch, then to the starter relay in the fusebox, and finally to the starter solenoid “S” terminal. The camshaft sensor provides DATA to the ECM or PCM. The ECM or PCM decides to send the signal to the starter relay to activate it.

When the starter relay is activated, it sends the current to the solenoid pin-type “S” terminal. When the “S” terminal receives the current, it pulls the plunger inside the solenoid making the connection between the two thicker terminals, and the current starts to flow directly from the battery to the starter motor assembly.

Related Post: 11 Parts Of Car Starter Motor & Functions

3 Pole Starter Solenoid Wiring Diagram

Starter Solenoid Terminals
Starter Solenoid Terminals

A 3-pole starter solenoid is usually also called a 3-terminal starter solenoid. It is the same starter solenoid we have discussed above. A 3-pole starter solenoid has three terminals at the back of the solenoid cap, one small terminal, and two thicker terminals.

The small terminal is called the “S” terminal, which stands for signal means the ignition switch signals the starter solenoid for activation through this terminal.

The other two terminals are thicker and larger in size, in which one terminal is a feed terminal and is connected to the battery-positive power source. The second thicker terminal is the output terminal and is connected to the starter motor assembly.

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What Wires Go To The Starter Solenoid

Diagram What Wires Go To The Starter Solenoid
Diagram What Wires Go To The Starter Solenoid

The starter solenoid wiring diagram is no more a mystery. It is very easy. If you don’t know what wires go to the starter solenoid. Here is a quick illustration.

  1. The Pin-types “S” terminal goes to the Ignition Switch.
  2. The Bolt-type Feed Terminal goes to the battery-positive power source.
  3. The Bolt-type Output Terminal goes to the starter motor assembly.

How to Wire a Starter Solenoid

Installing a starter solenoid requires three types of wire: the positive wire from the battery terminal, the wire going to the starter, and the thin pair of wires from the ignition switch circuit. The positive wire from the battery is connected to the starter solenoid’s positive terminal. Then, one of the thin wires from the ignition switch circuit is connected to the smaller metal stud terminals on the starter relay. Finally, a wire is connected from the starter solenoid to the starter motor. These connections should be done in accordance with the manufacturer’s instructions to ensure proper operation and safety. For a fully comprehensive explanation, read the following article.

Related Post: How To Wire A Starter Solenoid In 5 Min (With Diagram)

Wires: Does It Really Make a Difference

In regard to the question of whether the wiring in a car matters, it is necessary to consider the various implications of this concept. The wiring of the car has an important role in its overall functioning, as it provides the means by which electrical signals and energy can be properly distributed throughout the vehicle. Additionally, it is also responsible for providing a safe and efficient power supply that is able to support various components within the car.

The Essential Purpose of Starter Solenoids Uncovered

The starter solenoid is vital to the functioning of a vehicle due to its role as an electromechanical relay. In essence, it is responsible for connecting the battery with the starter motor, thus allowing the engine to be turned on. By providing an electrically controlled connection between these two components, it allows the necessary current to flow in order to energize the motor and begin the combustion process. As such, without this component present, a car would not be able to start.

Simple Techniques for Identifying Faulty Starter Solenoids

In order to ascertain whether a starter solenoid is operating at its optimal capacity, one must first assess the functional integrity of the device. Additionally, it is important to conduct an inspection of the physical integrity of the solenoid, ensuring that there are no major visual indicators of wear or damage.

  • Listen for a Clicking Sound Coming From the Starter Motor: If you hear successive clicking and grinding noises when you turn the ignition key, it is likely a sign that the starter solenoid is bad and needs to be replaced.
  • Unhook the Wires Across the Solenoid: Unhook the wires that go across the solenoid and turn the ignition key. Listen to the solenoid: if it clicks, proceed to further test.
  • Engine Doesn’t Crank or Start: If the starter solenoid switch is connected and your car does not turn on, it is likely that the starter solenoid is failing to turn the crankshaft, as a result, needs to replace the solenoid.
  • Intermittent Operation: If your car starts sometimes and not others, it is because the starter motor sometimes turns and the other time doesn’t. It is likely a sign of a failing starter solenoid.
  • Your Vehicle Labors to Crank or Cranks Slowly: If your vehicle labors to crank or cranks slowly, it is likely due to the battery not having enough power to fully engage the solenoid and turn over the engine flywheel.
  • Starter Fails to Engage: If the starter engages but does not disengage when you let go of the key, the solenoid is likely bad and the starter may suffer significant damage as a result.

Ignoring These Solenoid Wiring Mistakes Could be Costly

  • Not Testing the Starter Motor: Before you install the starter motor, be sure to thoroughly test it to make sure it is working properly. This is essential as faulty starter motors can prevent your entire system from working.
  • Not Securing Connections: Make sure all electrical connections are properly secured. Loose connections can cause an electrical arc, resulting in a fire or other dangerous situation.
  • Not Utilizing a Ground Wire: A ground wire is necessary in order to ensure proper power flow and a complete starting circuit to prevent electrical shocks. Make sure the ground wire is connected tightly to the starter motor and to the battery.
  • Not Using the Right Size Wire: The starter motor requires a specific size wire in order to provide the necessary power. Make sure you use the right size of wire for the job.
  • Not Using the Right Fuse: Fuses are used to protect wiring and the starter motor from any potential damage. Make sure you use the right type and size of fuse for the job.
  • Not Installing the Starter Motor Properly: Pay attention to how the starter motor is installed. Make sure it is installed correctly in order to ensure the proper functioning of the starter motor.
  • Not Testing the Wiring: Always test the wiring after it has been installed to make sure it is functioning properly. This will help you avoid any potential issues with the starter motor.
  • Not Following Safety Guidelines: Failing to adhere to established safety protocols related to the installation of starter solenoids can have potentially catastrophic consequences, including, but not limited to, electric shock, burns, and fires.

Frequently Asked Questions (FAQs)

How many wires go to the starter solenoid?

A typical starter solenoid has three wires, one wire goes from the starter solenoid to the starter motor and the two wires come to the starter solenoid from outside. One wire comes to the large terminal from the battery, and the other wire comes from the ignition switch. The solenoid is essentially a big electromagnet that closes a circuit between the battery and the starter motor. This allows current to flow to the starter motor, which then starts the engine.

Does a starter solenoid have to be grounded?

A starter solenoid is a device that helps to engage the starter motor in a vehicle. The solenoid is usually mounted on the starter itself, and when the key is turned to the “start” position, it activates the solenoid which then closes a circuit between the battery and the starter motor.

A starter solenoid must be grounded in order to function properly. Without a ground, the solenoid will not be able to complete the circuit and provide the necessary power to start the engine. It is grounded via the starter motor.

What are the 4 terminals on a starter solenoid?

A four terminal starter solenoid typically has four terminals: two terminals are used for the high-current circuit and the other two are the low-current terminals. The terminals are typically labeled “B” or “Battery,” “S” or “Start,” “I” or “Ignition,” and “R” or “15A.” The “B” or “Battery” terminal connects the solenoid directly to the positive battery cable. The “S” or “Start” terminal is the hot wire from the power supply. The “I” or “Ignition” terminal is connected to the starter. Finally, the “R” or “15A” terminal is connected to the ignition switch. Some starter solenoids may contain only three terminals, and the “R” terminal is then grounded through the mounting hardware.


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