How to Use a Relay in Car Electronics

Contributor

By eHow Contributing Writer

Article Rating: (39 Ratings)

A relay is an electromagnetic switch. When power or ground is applied to a coil, the relay clicks on or off. The result is that a power wire to a function is either closed (connected) or opened (disconnected). When the line is connected, the function is turned on and works. When the line is disconnected, the function is turned off and will not work. A relay can be used on alarm systems to disable the starter, to flash the parking lights, and more.

Difficulty: Moderate

Instructions

Using a Relay to Flash Your Car's Lights

Step 1

Read instructions that come with the alarm and relay.
Step 2

Apply constant 12 volts to poles 85 and 87.
Step 3

Put the lead from the alarm's output to pole 86. When negative pulse throws pole 86, poles 85 and 87 are already getting 12 volts. The switch is clicked and 12 volts are going from pole 87 to pole 30.

Using a Relay to Turn On an Amplifier

Step 1

Connect the remote-on lead from the head unit to pole 85.
Step 2

Apply ground to pole 86.
Step 3

Put positive voltage from the battery to pole 87.
Step 4

Attach the amplifier turn-on lead to pole 30.

Using a Relay to Set Up Starter Kill With a Hidden Toggle Switch

Step 1

Connect starter solenoid line to pole 87.
Step 2

Connect poles 30 and 85 to 12 volt accessory line.
Step 3

Connect toggle switch to pole 86 and ground the toggle switch.
Step 4

Connect the positive from the battery through a fuse and flashing LED to the toggle switch.
Step 5

Ground off of the battery.

Comments

HHOproject said

Flag This Comment

on 9/29/2008 HI anyone know how to connect a 12volt 60 amp relay# beuler bu-5083-0000 i have a device i like to controll it on & off with this relay the device pulls about 13 amp at 14 volts....any good ideas... no instructions included in box thanks don ps i know verry little when it comes to any relay......

Anonymous said

on 11/22/2005 When you are using any Pioneer deck, always use a relay to turn on more than one amp! Or else with time, your Pioneer will eventually die. This happens to many of the decks released before 2000 - premier and standard. Relays are easy to use; why risk it?