How do you know which door is causing door ajar light to stay on?

To identify which door is causing the "door ajar" light to stay on, first, visually inspect each door to ensure they are fully closed. Next, open and close each door one at a time while observing the dashboard light. If the light turns off after closing a specific door, that door is likely the culprit. Additionally, check the door switches for any signs of damage or malfunction, as faulty switches can also trigger the warning light.