How can a driver ensure that a trailer is properly secured after coupling?

A driver can ensure that a trailer is properly secured after coupling by performing a tug test to check that the trailer is locked onto the fifth wheel. This test involves applying a slight forward force on the trailer while it's still on the ground, which verifies that the locking mechanism of the fifth wheel has engaged effectively. If the trailer is not firmly attached, it will move, indicating that the connection is not secure. This process is crucial for safety, as it minimizes the risk of the trailer disconnecting while driving.

The other answers, while related to trailer management, do not specifically confirm that the trailer is securely coupled. Checking the trailer lights is important for safety but does not ensure that the coupling itself is secure. Adjusting the trailer brakes is essential for proper braking but does not relate to whether the trailer is latched on. Driving a short distance to test the coupling could be risky since it might lead to an accident if the trailer is not secure, rather than directly confirming the lock's integrity through a tug test.