What indicates a need for immediate repair in an air brake system?

The presence of unusual noise or vibration when the brakes are engaged in an air brake system is a strong indicator that immediate repair is necessary. Such symptoms can suggest underlying issues that may compromise the effectiveness and safety of the braking system. For instance, atypical noises might be associated with worn brake components, air leaks, or malfunctioning parts that could lead to brake failure. Additionally, vibrations can indicate problems with brake drums, linings, or other critical elements. Ignoring these signs can lead to dangerous driving conditions and increased risk of accidents.

The other options, while they may indicate problems, are not as urgent. A faint ticking sound might be related to normal wear and tear and does not typically signify an immediate or hazardous malfunction. Flickering dashboard lights can result from electrical issues unrelated to brake function, and having smoother brakes that feel softer could suggest air pressure issues but not necessarily an urgent situation requiring immediate action. Understanding the implications of unusual noises or vibrations is crucial for maintaining safety on the road.