2003 Chevrolet Avalanche 2500, 4WDFACTORY OEM SERVICE PROCEDURE

Engine Controls - System & Component Testing - 8.1L: Introduction

NOTE: Unless specified otherwise, Sierra and Silverado information also applies to Cab & Chassis Sierra and Cab & Chassis Silverado.

Before testing separate components or systems, follow proper workflow. See DIAGNOSTIC STARTING POINT - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 8.1L AVALANCHE, SIERRA, SILVERADO, SUBURBAN & YUKON XL article. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, proceed to NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 8.1L AVALANCHE, SIERRA, SILVERADO, SUBURBAN & YUKON XL article. If no DTCs are present and a driveability condition exists, proceed to SYMPTOMS in TROUBLE SHOOTING - NO CODES - 8.1L AVALANCHE, SILVERADO, SUBURBAN & YUKON XL article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

NOTE: Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.