Automotive Relay Circuit Guide

Automotive Relay Circuit Guide - Runs on all Phones & Tablets
(Includes circuit explanations, how current flows and how to wire relays from the ground up.)
By Mandy Concepcion

This book is a comprehensive work on automotive relays and their circuit analysis. The book is also a companion to our Video-DVD series of the same title. Here, we analyze how automotive relays are connected with their peripheral components. Each section starts with the specifics of the components used in that circuit and then there’s a deep analysis of how current flows on the circuit. The idea is to first explain and give the reader the particulars of each circuit, then go deeper and analyze why the circuit behaves the way it does, how to diagnose it and how to connect it in case the whole wiring is missing, obsolete or simply was never present to begin with. Special thanks to Carmen Diaz for her invaluable input on the cover layout, structure, arrangement and proofing.

Table of Contents

How to wire relay as ON button – Explains how to connect an automotive relay to stay ON at all times. Useful for any device that stays ON and using a low current trigger switch.

Turn ON relay button diode – Details the use of a Diode as an ON circuit. The diode itself is the key to it all.

How to make a relay injector security circuit – This is a clever circuit for deactivating your vehicle’s fuel injectors as a security measure. It’s simple and concealed.

How to wire a relay starter kill-switch – Disabling the starter is fairly simple, but this circuit also employs other tactics to make it more effective.

How to do a single relay car alarm – Shows how to wire a relay as an easy to connect car alarm. It’ll show you a cost effective way to secure your car.

How to connect a power relay – Gives you extensive input for connecting an automotive relay as a power unit or to drive almost any kind of device.

How to wire a cooling fan relay – Useful in retrofitting an older systems to work with electric cooling fans and to replace an out of production fan with a universal unit.

How to connect a fuel pump relay – There are many instances where the fuel pump has gone bad an no replacement is available. Learn how this circuit works and how to wire the fuel pump.

How to do an alternator relay failure circuit – A very clever circuit used as a warning to the driver when an impending alternator issue is at hand.

How to wire relay power door lock – Power door locks have been around for many years. This section shows you how the circuit works, how to connect it, retrofitting to an older car and how to repair the systems in case of failure.

How to wire a power windows relay – Resistive rest at ground or any other wiring scheme is foreign to many people. Learn how it works right here in this article.

How to make a relay turn signal – Learn how to wire an entire high class turn signal system, found on luxury makes. Useful for retrofitting your own vehicle in case parts are no longer available.

How to wire an AC compressor clutch relay – A very reliable circuit is presented here to bow help you understand an AC systems as well as teaches you to retrofit older cars.

How to connect a headlight warning relay – Knowing when the headlights are down is essential. This circuit will show you how the circuit works and how to build it.

How to wire an ECM relay – The ECM relay meets all power requirements for the car computer. Learn how the circuit works and how to connect it.

How to wire AC blower motor relay – Get the details on connecting an AC blower motor and how to re-wire a new one if needed.

How to wire relay fog lights – Fog lights are necessary in many areas. Most vehicles have no fog-lights and this circuit is geared towards explaining how they work and install them.