Toyota Sienna keyless entry, dome lights, and door locks not working with flickering headlights and fast idling issue, suspected faulty computer box on Toyota Sienna

Submitted by Firerider1 · Jun 23, 2025
Published by RepairPal

Problem overview

Some Toyota Sienna owners report experiencing issues with keyless entry, power door locks, and dome lights, which may be linked to a faulty COMPUTER, MULTIPLEX NETWORK BODY that controls these functions. Additionally, these electrical problems could potentially lead to flickering headlights, prompting a recommendation for a thorough inspection of the vehicle's electrical system. While fast idling issues are not directly mentioned, owners suspecting a faulty computer box may find that it affects engine performance, including idle speed. If the computer box or ECU is suspected to be malfunctioning, it is crucial to have it diagnosed and possibly replaced by a qualified mechanic, as it plays a vital role in controlling various vehicle systems. Utilizing the OBD-II Diagnostic Port and Diagnostic Trouble Codes (DTCs) can aid in troubleshooting the Smart Entry and Start System issues. Overall, a comprehensive inspection by a professional is advised to accurately identify and address these concerns.

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