Engine Controls - Basic Diagnostic Procedures: Introduction

The following diagnostic steps will help prevent overlooking a simple problem. The first step in diagnosing any driveability problem is verifying the symptom(s) with a test drive under the conditions the problem reportedly occurred.

Before proceeding with diagnostics, check for applicable Technical Service Bulletins (TSBs). If there are no applicable TSBs, perform QUICK TEST under SELF-DIAGNOSTICS - EEC-V - CNG, FLEX-FUEL & GASOLINE to identify Diagnostic Trouble Codes (DTCs). If no DTCs are present or only pass codes are found during self-diagnostics and symptom is present, proceed to TROUBLE SHOOTING - NO CODES - EEC-V - CNG, FLEX-FUEL & GASOLINE article for diagnosis by symptom.