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Engine Control System Self-Diagnostics: Introduction

NOTE: Before performing testing procedures, check for any related Technical Service Bulletins (TSBs).
NOTE: When battery is disconnected on Sienna, power sliding doors will need to be initialized. See SLIDING DOOR INITIALIZATION PROCEDURE (SIENNA) in COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

To properly diagnosis and repair this vehicle, follow TESTING PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. If no Diagnostic Trouble Codes (DTC) are present and a no start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).