1. Consult your owner's manual: This is the most reliable way to find its exact location and which relay it is. The manual should have a fuse box diagram.
2. Look for a fuse box diagram online: If you don't have the manual, searching online for "2004 Chevy Impala fuse box diagram" will give you a picture that shows the location of all the relays and fuses. You'll need to identify the one labeled "turn signal" or "flasher."
3. Examine the relays themselves: Once you've located the underhood fuse box, carefully examine the relays. They usually have a small marking indicating their function.
Keep in mind that there might be slight variations depending on trim level and options. Using your owner's manual or an online diagram specific to your Impala is crucial for accurate identification.