A 12-volt solenoid relay is an electrical component that helps switch a high-amperage load with a low-amperage signal. It is commonly used in automotive applications, and understanding the wiring diagram is essential for proper installation and operation. In this article, we will discuss the 12-volt solenoid relay wiring diagram in detail.
What is a 12-Volt Solenoid Relay?
A solenoid relay is an electromagnetic switch that allows a low voltage signal to control a high voltage and/or high amperage load. A 12-volt solenoid relay, as the name suggests, is a relay that operates on 12 volts DC.
The primary function of a 12-volt solenoid relay is to switch a high-amperage load using a low-amperage signal, such as the signal from a switch or an electronic control module (ECM). It is commonly used in automotive and marine applications, where it is used to control various systems such as starter motors, winches, and hydraulic systems.
How Does a 12-Volt Solenoid Relay Work?
A 12-volt solenoid relay consists of two parts: the coil and the contacts. The coil is an electromagnetic coil that generates a magnetic field when a low voltage signal is applied to it. The contacts are the switch that opens and closes the circuit to the load.
When a low voltage signal is applied to the coil, it generates a magnetic field that pulls the contacts closed, allowing current to flow to the load. When the signal is removed, the magnetic field collapses, and the contacts open, interrupting the current flow to the load.
12-Volt Solenoid Relay Wiring Diagram
Below is the wiring diagram for a typical 12-volt solenoid relay. The diagram shows the coil connections, the contact connections, and the battery and load connections.
| Terminal | Description |
|---|---|
| 85 | Coil ground |
| 86 | Coil positive |
| 30 | Battery positive |
| 87 | Load positive |
| 87a | Normally closed contact |
Terminal Descriptions
85: Coil ground. This terminal is connected to a ground source, typically the vehicle chassis or battery negative.
86: Coil positive. This terminal is connected to the low voltage signal that activates the relay coil. This can be a switch, an electronic control module, or another source of low voltage signal.
30: Battery positive. This terminal is connected to the positive terminal of the battery or power source. It provides power to the relay coil and the load.
87: Load positive. This terminal is connected to the positive terminal of the load, such as the starter motor or winch. When activated, the relay switches power from terminal 30 to the load.
87a: Normally closed contact. This terminal is normally connected to terminal 30, providing a continuous circuit to the load. When the relay is activated, this contact opens, interrupting the circuit to the load.
Wiring Diagram Example
Here is an example of how the 12-volt solenoid relay wiring diagram can be used in a real-world application:
Scenario: Installing a winch on a vehicle.
- Connect the winch positive cable to the load positive terminal (87) on the relay.
- Connect the winch negative cable to the vehicle chassis or battery negative.
- Run a cable from the vehicle battery positive terminal to the relay battery positive terminal (30).
- Connect a switch to the low voltage signal input terminal (86) on the relay. This switch can be a toggle switch, a push-button switch, or another type of switch that allows a low voltage signal to be applied to the relay coil.
- Connect the switch ground to the vehicle chassis or battery negative.
- Connect the relay coil ground (85) to the vehicle chassis or battery negative.
- Connect the switch positive to the relay coil positive (86) terminal.
Frequently Asked Questions
What is the maximum amperage a 12-volt solenoid relay can handle?
The maximum amperage a 12-volt solenoid relay can handle varies depending on the specific model and manufacturer. It is important to choose a relay that is rated for the amperage of the load it will be controlling. Typical amperage ratings range from 30 amps to 200 amps.
Can a 12-volt solenoid relay be used to control AC loads?
No, a 12-volt solenoid relay is designed to control DC loads only. If you need to control an AC load, you will need to use an AC relay.
Can a 12-volt solenoid relay be used to control multiple loads?
Yes, a 12-volt solenoid relay can be used to control multiple loads by connecting them in parallel to the load positive terminal (87) on the relay. It is important to ensure that the combined amperage of the loads does not exceed the amperage rating of the relay.
Can a 12-volt solenoid relay be used to control a negative-grounded load?
Yes, a 12-volt solenoid relay can be used to control a negative-grounded load by connecting the load negative to the vehicle chassis or battery negative, and connecting the load positive to terminal 87a on the relay.
What is the purpose of the normally closed terminal (87a) on the relay?
The normally closed terminal (87a) on the relay provides a continuous circuit to the load when the relay is not activated. This can be useful in applications such as automotive lighting, where a relay can be used to switch between high and low beam headlights. When the relay is not activated, the normally closed terminal provides power to the low beam headlights. When the relay is activated, the normally closed terminal opens, interrupting the circuit to the low beams and allowing power to flow to the high beam headlights.
Conclusion
A 12-volt solenoid relay is a useful component in automotive and marine applications, allowing a low-amperage signal to control a high-amperage load. Understanding the wiring diagram and proper installation is essential for proper operation. By following the guidelines in this article, you can ensure that your 12-volt solenoid relay is properly installed and functioning as intended.
