Toyota Sienna 2007 Operating Manual page 202

If the indicator or buzzer comes on...
(o) (o)
Third seats warning light
and buzzer
Dynamic laser cruise control
(p)
master warning light
(q)
Key reminder buzzer
07 SIENNA_U (L/O 0612)
Check if third seat operation is completed.
Check if an object is caught between third seat and seatback and/or between third
seat and floor. If nothing is caught, contact Toyota dealer.
Check condition according to warning code. If system malfunctions, contact Toyota
dealer.
Remove key.
Do this.
2007 SIENNA from Oct. '06 Prod. (OM45437U)
193