On-Board Diagnostic (Engine Control System BP, BP With TC]: Foreword

When the customer reports a vehicle malfunction, check the malfunction indicator light (MIL) indication and diagnostic trouble code (DTC), then diagnose the malfunction according to following flowchart.
- If a DTC exists, and the MIL does not illuminate or flash, diagnose the applicable symptom troubleshooting. See SYMPTOM DIAGNOSTIC INDEX .
- If no DTC exists and the MIL does not illuminate or flash, diagnose the applicable symptom troubleshooting. See SYMPTOM DIAGNOSTIC INDEX .
Fig 1: Diagnosis System Block Diagram
Courtesy of MAZDA MOTORS CORP.