Engine Controls - Tests W/O Codes - Gasoline: Introduction

NOTE: These models may use Electronic Control Modules (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM). PCM will be used in this article to describe all control modules.

Before diagnosing symptoms or intermittent faults, perform steps in appropriate BASIC TESTING and TESTS W/CODES articles below. Use this article to diagnose driveability problems if a hard fault code is not present or if vehicle is not equipped with a self-diagnostic system.

Symptom checks are intended to direct the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to either specific component or system testing or an adjustment specification. Use intermittent test procedures to locate driveability problems which DO NOT occur when the vehicle is being tested.

NOTE: For specific testing procedures, see appropriate SYSTEM/COMPONENT TESTING article. For specifications, see appropriate ADJUSTMENTS or SPECIFICATIONS article in the ENGINE PERFORMANCE section below.

NOTE: SERVICE ENGINE SOON light, located on instrument cluster, is also referred to as the Malfunction Indicator Light (MIL).