The rear ABS sensors on a 2003 Chevy Avalanche 1500 are located on the
inside of the rear wheel hubs. This means you'll need to remove the wheels to access them. They're typically mounted within the hub assembly itself, and are small, cylindrical sensors with a wire harness extending from them.
Important Note: There's one sensor per rear wheel (driver's side and passenger's side). To be certain of their exact location, consult a repair manual specific to your 2003 Chevy Avalanche 1500. A diagram will show you their precise positioning within the hub assembly.
