Section 42 (ENGINE CONTROLS - TROUBLE SHOOTING - NO CODES - 6.0L W/BiFuel & CNG): Introduction

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Savana, 2003 Chevrolet Silverado, and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Unless indicated otherwise, Savana includes Savana Special.

Before diagnosing symptoms or intermittent faults, follow proper workflow. See DIAGNOSTIC SYSTEM CHECK - ALTERNATIVE FUELS - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 6.0L SILVERADO & SIERRA - BI-FUEL & CNG article or DIAGNOSTIC SYSTEM CHECK - ALTERNATIVE FUELS - ENGINE CONTROLS in SELF-DIAGNOSTICS - 6.0L CHEVY EXPRESS & SAVANA - BI-FUEL & CNG article. If no Diagnostic Trouble Codes (DTC) are present and a no start condition exists, proceed to 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, diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or computer control unit. Check with manufacturer for latest chip or computer application.

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing.

NOTE: For specific testing procedures, see SYSTEM & COMPONENT TESTING - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article. For specifications, see ON-VEHICLE ADJUSTMENT - TRUCKS - EXCEPT TRACKER or SERVICE & ADJUSTMENT SPECIFICATIONS - 6.0L CHEVY EXPRESS, ESCALADE, HUMMER H2, SAVANA, SIERRA, SILVERADO, YUKON & YUKON XL article.