CDL Pre-Trip: Coupling Inspection (Air Lines & Electrical) Description: In this video, we cover the CDL pre-trip coupling inspection, focusing on the air lines, service line, O-rings, seals, and electrical connections. Learn how to properly explain checking for damaged or missing O-rings, preventing air leaks, and ensuring the electrical plug is fully connected with no bent pins. These steps are critical for trailer lights and air system safety—and for earning points on your CDL exam. Perfect fo