To find it, you'll need to:
1. Locate the underhood fuse box: This is usually a black plastic box near the battery.
2. Open the fuse box: You'll likely need to either remove a cover or unlatch it. Consult your owner's manual for specifics.
3. Consult the fuse box diagram: The inside of the lid (or a diagram inside your owner's manual) will show the location of the flasher relay. It might be labeled as "flasher," "turn signal flasher," or have a symbol depicting a flashing light.
If you can't find it using the diagram, a search online for "[your Cobalt's year and model] fuse box diagram" should bring up a helpful image.