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. For a no-start condition, verify events at time of failure to start.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, are, poor electrical connections or damaged/misrouted vacuum hoses. See VACUUM DIAGRAMS article, this will assist in identifying improperly routed vacuum hoses which cause driveability and/or computer-indicated malfunctions. Before condemning the computerized system, perform each test listed in this article.