Section 448 (Engine Controls Self-Diagnostics - 6.0L Bi-Fuel & CNG): Summary
WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, see NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article. If no DTCs are present and a driveability condition exists, see SYMPTOMS in TROUBLE SHOOTING - NO CODES - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.).