Auto relay wiring is important in the functioning of a vehicle’s electrical system. A relay is an electromagnetic switch that helps to control high-power devices through low-power control signals. In a vehicle, relays are used to control various components such as lights, horns, and motors for windows and doors. This article will discuss the 12v auto relay wiring diagram in detail.
What is a Relay?
A relay is an electrical switch that uses an electromagnetic force to open or close contacts. It works by applying a voltage to the coil, which generates a magnetic field. This magnetic field operates a set of contacts, which either open or close depending on the state of the coil. Relays can be used to control a range of high-power devices with a low-power control signal.
Relays come in different shapes and sizes, with different ratings and specifications. The type of relay used in a vehicle depends on the specific application it is intended for. The most common type of relay used in vehicles is the 12v auto relay.
The 12v Auto Relay Wiring Diagram
The 12v auto relay wiring diagram shows how a relay is connected in a vehicle’s electrical system. The diagram consists of the power source, relay coil, relay contacts, and the device being controlled. The diagram also shows the wiring connections between these components.
Power Source
The power source for the relay is usually the battery. The positive terminal of the battery is connected to the input terminal of the relay. The negative terminal of the battery is connected to the ground or chassis of the vehicle.
Relay Coil
The relay coil is the part of the relay that generates the magnetic field that operates the contacts. The coil is usually connected to a low-power control signal such as a switch or a computer. When the control signal is applied, the coil generates a magnetic field that switches the contacts.
Relay Contacts
The relay contacts are the part of the relay that physically makes or breaks the connection between the device being controlled and the power source. The contacts can be either normally open (NO) or normally closed (NC). When the coil is not energized, the contacts are in their default state. When the coil is energized, the contacts switch from their default state to the opposite state.
Device Being Controlled
The device being controlled is the high-power device that is being turned on or off by the relay. This device can be anything such as a light, horn, or motor. The wiring connections between the device and the relay contacts are shown in the wiring diagram.
How to Wire a 12v Auto Relay
Wiring a 12v auto relay is a straightforward process. The first step is to identify the relay connections. The relay usually has four or five terminals. The terminals are labeled as follows:
- Input Terminal (30)
- Normally Open Contact (NO) (87)
- Normally Closed Contact (NC) (87a)
- Output Terminal (Common) (86)
- Optional Coil Suppression Diode (85)
Step 1: Connecting the Power Source
The first step is to connect the positive terminal of the battery to the input terminal (30) of the relay. The negative terminal of the battery is connected to the ground or chassis of the vehicle.
Step 2: Connecting the Device Being Controlled
The device being controlled is connected to either the normally open contact (NO) (87) or the normally closed contact (NC) (87a) of the relay. If the device needs to be turned on when the relay is energized, it should be connected to the normally open contact (NO) (87) of the relay. If the device needs to be turned off when the relay is energized, it should be connected to the normally closed contact (NC) (87a) of the relay.
Step 3: Connecting the Control Signal
The control signal is connected to the coil terminals of the relay. The control signal can be a switch or a computer. When the switch is turned on or the computer sends a signal, the coil is energized, which switches the contacts.
Step 4: Optional Coil Suppression Diode
An optional coil suppression diode can be connected between the coil terminals of the relay. The coil suppression diode helps to protect other components in the electrical system from voltage spikes that can be generated when the relay is turned off.
Frequently Asked Questions
Q: What is a 12v auto relay used for?
A: A 12v auto relay is used to control high-power devices in a vehicle’s electrical system such as lights, horn, and motors for windows and doors.
Q: How do I know which relay to use in my vehicle?
A: The type of relay to use in a vehicle depends on the specific application it is intended for. Check the vehicle’s owner’s manual or consult a professional mechanic to determine the appropriate type of relay to use.
Q: Can I use a 24v auto relay in a 12v system?
A: No, a 24v auto relay cannot be used in a 12v system. The voltage rating of the relay must match the voltage of the electrical system it is being used in.
Q: What is the difference between a normally open contact and a normally closed contact?
A: A normally open contact (NO) is a contact that is open or not connected when the relay is not energized. When the relay is energized, the contact closes or connects. A normally closed contact (NC) is a contact that is closed or connected when the relay is not energized. When the relay is energized, the contact opens or disconnects.
Q: What is a coil suppression diode?
A: A coil suppression diode is an optional component that is connected across the coil terminals of a relay. The diode helps to protect other components in the electrical system from voltage spikes that can be generated when the relay is turned off.
Conclusion
A 12v auto relay is an important component in a vehicle’s electrical system. It helps to control high-power devices through low-power control signals. Wiring a 12v auto relay is a straightforward process that requires connecting the power source, device being controlled, and control signal. To determine the appropriate type of relay for a vehicle, consult the owner’s manual or a professional mechanic.
