Honda Odyssey Owners Manual: Automatic Lighting Off Feature

The headlights, all other exterior lights, and the instrument panel lights turn off within 15 seconds after you remove the key and close the driver's door.
►You can change the headlight auto off timer setting.

If you turn the ignition switch to LOCK with the headlight switch on, but do not open the door, the lights turn off after 10 minutes (3 minutes, if the switch is in the AUTO position).

The lights turn on again when you unlock or open the driver's door. If you unlock the door, but do not open it within 15 seconds, the lights go off. If you open the driver's door, you will hear a lights on reminder chime.