Engine Controls - Self-Diagnostics: Introduction

Since many computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) when a malfunction occurs, check for Powertrain Control Module (PCM) DTCs prior to testing an individual system or component. Perform QUICK TEST  procedures. The self-diagnostic system can be accessed using an OBD-II compliant scan tool. If no DTCs are present, perform SYMPTOM DIAGNOSIS under SYMPTOMS in TROUBLE SHOOTING - NO CODES - VILLAGER article to diagnose driveability problems existing when a hard fault code is not present.