Engine Controls - Basic Testing: 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 to verify the customer's complaint with a test drive under the conditions the problem reportedly occurred.
Before entering self-diagnostics, perform a thorough 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 in this article.
NOTE:
Any references to ALDL connector should be interpreted as Data Link Connector (DLC), located on ECM, behind passenger kick panel.
NOTE:
Unless stated otherwise in test procedure, perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance.