Which is an important step in the lane change procedure for combination vehicles?

An important step in the lane change procedure for combination vehicles is to check mirrors and signal. This step ensures that the driver is aware of their surroundings and can safely execute the lane change. By checking mirrors, the driver can see vehicles in adjacent lanes and assess the space available for merging. This is especially critical for combination vehicles, which have larger blind spots and require more room to maneuver than standard vehicles.

Signaling is essential as it communicates the driver's intent to other road users, enhancing safety during the lane change. By both checking mirrors and signaling, the driver takes comprehensive precautions that increase awareness on the road, minimizing the risk of accidents.

Relying solely on mirrors is insufficient because it doesn’t account for areas that may not be visible in the mirrors. Using the horn can be considered in specific situations but is not a standard practice and could be misinterpreted by other drivers. Only checking blind spots fails to provide a complete picture of the vehicle's surroundings, as it neglects the information provided by mirrors and does not involve signaling. Thus, combining these actions is critical for safe lane changes in combination vehicles.