Why the fuel light comes on . your 2002 trailblazer?

The fuel light in your 2002 Trailblazer comes on because the fuel level in the tank has reached a pre-determined low point. This is a warning system to alert you that you need to refuel soon to avoid running out of gas. The exact level at which the light illuminates varies slightly depending on the vehicle's configuration and the sensor's accuracy, but it generally indicates you have only a gallon or two left, sometimes less.