The 5 Primary Types of Automotive Signals

INTRODUCTION

Let us begin by learning what primary types of signals are found in today's vehicle systems. We will take an overview look at the five primary types of signals found in today's vehicles, and what sensors, devices or circuits use them.

Think of the five primary signal types as the building blocks of intelligent electronic communication between sensors, control units and other devices in the system. The five primary signal types are similar to the letters in the alphabet of the English language. They each have different electronic "sounds," if you will. In electronic terms, they are "pronounced" differently, and are even used for different communicative purposes.

We will then dig deeper into each one of the signals separately, and explore their individual "critical features." Finally, we will see if we can put the building blocks, the "electronic letters" if you will, and the "electronic words" together, so we can understand the universal language of intelligent electronic communication.


THERE ARE 5 PRIMARY SIGNAL TYPES FOUND IN AUTOMOBILES

1. DIRECT CURRENT (DC) SIGNALS

The types of sensors or devices in a vehicle that produce DC signals are:

^ Power supplies such as battery voltage or sensor reference voltages created by the PCM.

^ Analog sensor signals, such as engine coolant temperature, intake air temperature throttle position, EGR valve position, oxygen, vane and hot wire mass airflow, vacuum and temperature switches, throttle switches, and GM, Chrysler and Asian manifold absolute pressure sensors.

2. ALTERNATING CURRENT (AC) SIGNALS

The types of sensors or devices in a vehicle that produce AC signals are:

^ Magnetic Camshaft (CMP) and Crankshaft (CKP) position sensors

^ Antilock Brake System (ABS) wheel speed sensors

^ Vehicle Speed Sensors (VSS)

^ Knock Sensors (KS)

3. FIXED PULSE WIDTH SIGNALS

The types of sensors or devices in a vehicle that produce Fixed Pulse Width Signals are:

^ Hall Effect, CMP and CKP sensors

^ Digital mass airflow sensors

^ Ford MAP sensors

^ Optical VSS

^ Camshaft (CMP) and Crankshaft (CKP) sensors

4. PULSE WIDTH MODULATED SIGNALS

The types of circuits or devices in a vehicle that produce Pulse Width Modulated Signals are:

^ Fuel injectors

^ Electronic spark timing circuits

^ EGR control solenoids

^ Idle air control motors and solenoids

^ Ignition coil primary

5. SERIAL DATA (Multiplexed) SIGNALS

The type of device in a vehicle that produces Serial Data Signals is the Powertrain Control Module (PCM) or Body Control Module (BCM), if the vehicle manufacturer has equipped the Control Module with self diagnostics or other serial data/communications capability.


Now that we've learned the five primary types of automotive electronic signals and their associated sensor or device groupings, let's find out what else is critical to know about automotive electronic signals. OK, we know the five primary signal types are; DC, AC, FIXED PULSE WIDTH, PULSE WIDTH MODULATED, and SERIAL DATA signals. Now let's move on to the five "Critical Dimensions" of the automotive electronic language puzzle. The 5 Critical Dimensions