Preliminary Checks

• Verify the on-vehicle diagnostics are working by performing ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in TESTS W/CODES article.
• On all modes, ensure PCM and MIL function properly.
• Ensure no trouble codes (except intermittent) are stored.
• Ensure fuel control system operates properly. See BASIC TESTING article.
• Perform fuel system pressure test.
• Visually inspect all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. Not all items listed under each symptom apply to all models and systems. These procedures normally recommend testing of a specific system or component, such as EGR, EST, TCC, etc. See SYSTEM/COMPONENT TESTS article for test procedures.