Engine Controls - Basic Testing - Non-Turbo: Introduction
NOTE:
In this article, Engine Control Module (ECM) may also be referred to as Engine Control Unit (ECU).
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 complaint with a test drive under the conditions the problem reportedly occurred.
Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/ misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.
NOTE:
Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless otherwise instructed in test procedure.