The vehicle has a battery saver feature designed to protect the vehicle's battery.
When any interior lamp is left on and the ignition is turned off, the battery rundown protection system automatically turns the lamp off after 20 minutes.
This prevents draining of the battery.
Chevrolet Cobalt Service & Repair Manual. Noise, Diagnosis
A visual inspection must always
be performed to confirm the presence of aftermarket components, potential
collision damage, or areas of concern.
A noise produced by a vibration
can be diagnosed in the same manner as a vibration. A noise produced by
wind, leaks, or ...