Starting a vehicle’s engine is a crucial process, especially in the mechanical universe of automobiles. One crucial component in this process is the starter relay. The starter relay circuitry is responsible for allowing the starter motor to engage the engine, resulting in the engine starting. In this article, we will discuss starter relay wiring diagrams, their types, and how they function.
What is a Starter Relay?
A starter relay is an electromechanical switch that uses a small amount of current to control a much larger amount of current. Starter relays typically control the starter solenoid which is in turn responsible for engaging the starter motor to crank the engine. Without the starter relay, a vehicle’s engine will not turn over.
The starter relay is activated by the ignition switch, which allows current to flow through the relay coil. This current then pulls the contacts of the starter relay together, completing the circuit between the battery and the starter solenoid, allowing current to flow to the starter motor which cranks the engine.
Types of Starter Relay Wiring Diagrams
There are two types of starter relay wiring diagrams: four-pin and five-pin.
Four-Pin Starter Relay Wiring Diagram
A four-pin starter relay wiring diagram typically has four pins or terminals:
| Pin | Description |
|---|---|
| Pin 85 | This pin is connected to the ground. |
| Pin 86 | This pin is connected to the control circuit of the ignition switch. |
| Pin 87 | This pin is connected to the starter motor solenoid. |
| Pin 30 | This pin is connected to the battery’s positive terminal. |
The wiring diagram for a four-pin starter relay is as follows:
Pin 85: This pin is connected to the ground or “-“ terminal of the battery.
Pin 86: This pin is connected to the ignition switch. When the ignition switch is turned to the “START” position, the control circuit for the relay is activated, allowing current to flow through the coil of the relay.
Pin 87: This pin is connected to the starter motor solenoid. When the relay contacts close, power flows from the battery to the solenoid, which activates the starter motor and cranks the engine.
Pin 30: This pin is connected to the battery’s positive terminal. This provides the voltage necessary to operate the relay.
Five-Pin Starter Relay Wiring Diagram
A five-pin starter relay wiring diagram typically has five pins or terminals:
| Pin | Description |
|---|---|
| Pin 85 | This pin is connected to the ground. |
| Pin 86 | This pin is connected to the control circuit of the ignition switch. |
| Pin 87a | This pin is connected to the starter motor solenoid. |
| Pin 87 | This pin is connected to the battery’s positive terminal. |
| Pin 30 | This pin is connected to another device (for example, a fuel pump). |
The wiring diagram for a five-pin starter relay is as follows:
Pin 85: This pin is connected to the ground or “-“ terminal of the battery.
Pin 86: This pin is connected to the ignition switch. When the ignition switch is turned to the “START” position, the control circuit for the relay is activated, allowing current to flow through the coil of the relay.
Pin 87a: This pin is connected to the starter motor solenoid. When the relay contacts are in their “normally closed” position, power flows from the battery to the solenoid, which deactivates the starter motor.
Pin 87: This pin is connected to the battery’s positive terminal. This provides the voltage necessary to operate the relay when the ignition switch is in the “RUN” position.
Pin 30: This pin is connected to another device, such as a fuel pump. When the ignition switch is in the “START” position, current flows between pins 86 and 87. When the ignition switch is in the “RUN” position, current flows between pins 87 and 30.
FAQs
1. How do I know if my starter relay is bad?
If your engine won’t turn over when you turn the key, there is a good chance that your starter relay is bad. Other signs of a bad starter relay include a starter that engages but won’t turn, a clicking sound when you turn the ignition, or intermittent engine starting troubles. A certified mechanic can diagnose and fix a bad starter relay.
2. Can I bypass the starter relay?
Yes. If you suspect that your starter relay is bad, you can bypass it to see if your starter motor works. However, bypassing the starter relay should only be a temporary measure. If your engine starts when you bypass the starter relay, you should replace the relay as soon as possible.
3. Can I use a four-pin relay in place of a five-pin relay?
Yes. A four-pin relay can be used in place of a five-pin relay, but not vice versa.
4. How much does it cost to replace a starter relay?
The cost of replacing a starter relay varies depending on the make and model of your vehicle. Typically, the cost of replacing a starter relay ranges from $50 to $200, including labor costs.
5. Can I replace a starter relay on my own?
If you have some experience working on vehicles, you can replace a starter relay on your own. However, if you are not familiar with vehicle electrical systems, it is best to have a certified mechanic replace your starter relay.
Conclusion
The starter relay is a critical component in starting a vehicle’s engine. Knowing the wiring diagram for a starter relay is vital in troubleshooting and replacing it if necessary. By understanding the wiring diagram, you can diagnose and repair starter-related issues in your vehicle with ease.
