If the door open warning light is on but you believe all your doors and trunk are closed, there may be a mechanical issue with a door switch. (yourmechanic.com)
The lift gate open Warning Light is located on the instrument panel. (yourmechanic.com)
The advanced instrument panel houses a digital tachometer, LCD display with digital clock and temperature / mileage gauges, headlights on and door open warning buzzer. (cardekho.com)