PT Cruiser, 2001 - 2005

Introduction

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Powertrain Subsystems



A key to the diagnosis of the PCM and its subsystems is to determine which subsystems are on a vehicle. Examples of typical subsystems appear below:



Cranking & Charging System
 
Emission Control Systems
 
Engine Cooling System
 
Engine Air/Fuel Controls
 
Exhaust System
 
Ignition System
 
Speed Control System
 
Transaxle Controls
 

System Control Modules



Before attempting diagnosis of the Electronic Engine Control system, familiarize yourself with the basics of how the system is designed to operate. It consists of a central processing unit: Powertrain Control Module (PCM), Engine Control Module (ECM), Transmission Control Module (TCM) and/or the Body Control Module (BCM). These units are the heart of the electronic control systems on the vehicle. In some cases, these units are integral with one another, and on some applications, they are separate. As you get deeper into actual diagnostic testing, you will find out which units are used on the vehicle you are testing.

The PCM is a digital computer that contains a microprocessor. The PCM receives input signals from various sensors and switches that are referred to as PCM inputs. Based on these inputs, the PCM adjusts various engine and vehicle operations through devices that are referred to as PCM outputs. Examples of the input and output devices are shown in the graphic below.

Click image to see an enlarged view

Fig.



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Fig.

 
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