Engine Controls - Basic Diagnostic Procedures: Introduction

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Performing a thorough Visual Inspection and checking for DTCs may pinpoint faulty circuit, (vacuum or electrical) and/or faulty component or adjustment. See VISUAL INSPECTION  . After performing Visual Inspection, check for DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Most engine control problems result from mechanical breakdowns, poor electrical connections, or damaged/misrouted vacuum hoses.