CDL Vehicle Combination Practice Test

Coupling the glad hands together is a good practice when uncoupling because it helps prevent dirt and debris from entering the air lines, which can cause issues with the braking system. By coupling the glad hands, the air pressure is contained within the system, minimizing the risk of contamination and ensuring that the connections remain clean and functional for future use. This action also serves to protect the equipment, extending its longevity and reliability.

The other options don't provide the same level of protection or efficiency. Leaving the glad hands disconnected can expose the air lines to dirt and moisture, which can lead to brake failures. Hanging the electrical cable with the plug end up does not safeguard the connection from contaminants and can create potential hazards. Storing connections loosely could lead to tangling or damage to the cables and hoses, which may compromise the vehicle's functionality. Thus, coupling the glad hands is the most effective way to maintain the integrity of the air system during the uncoupling process.