What is the most likely cause of a scraping sound coming from one rear brake that stops when the brakes are applied?

The most likely cause of a scraping sound coming from one rear brake that stops when the brakes are applied is a broken shoe hold-down spring or pin. This component plays a crucial role in keeping the brake shoes securely positioned against the backing plate. When the hold-down spring or pin is damaged or broken, the brake shoes can shift during driving, causing them to scrape against other components such as the brake backing plate or drum. When you apply the brakes, the shoes press against the drum, stabilizing their position and temporarily stopping the scraping noise.

Other options, while they may indicate different issues, do not specifically correlate to the symptoms described. For example, a worn brake rotor might produce noise but would typically not cease when the brakes are applied. Insufficient brake fluid primarily affects braking performance and does not cause scraping sounds. A faulty ABS module relates to the overall electronic braking system and would unlikely cause a localized scraping noise from the brake assembly. Thus, the broken shoe hold-down spring or pin is the most fitting explanation for a noise that stops with brake application.