How do you reset alarm system for 2003 Toyota Highlander security system?

To reset the alarm system for a 2003 Toyota Highlander, first ensure that all doors are closed. Insert the key into the ignition and turn it to the "On" position without starting the engine. Press the "Lock" button on the remote key fob, or use the door lock switch to lock and unlock the driver's door. This should reset the alarm system. If the alarm continues to trigger, consult the owner's manual or a professional for further assistance.