How to Reset the Anti-Theft Lock on a Lexus LS400 Sedanby David Clair
The 2000 Lexus LS 400 sedan included an anti-theft system with an immobilizer. If any of the doors, the trunk or the hood is forcibly unlocked, or the battery terminal is disconnected and reconnected with the vehicle locked, the alarm will activate. The alarm blows the horn intermittently, the taillights, headlights and other exterior lights flash, and the engine will not start when it is activated. This condition will remain until you reset the alarm system.
Turn the ignition key to the "LOCK" position. Remove the key.
Close and lock all the doors, the trunk and the hood. Wait about 30 seconds until the security indicator flashes.
Insert the key into the driver or passenger front door. Unlock the door. The turn signals flash twice to indicate that the system has reset.