What should you do before starting a downhill with a loaded vehicle?

Before starting a downhill with a loaded vehicle, it is essential to downshift to a lower gear. This action allows the engine to assist in controlling the vehicle's speed through engine braking, which is crucial when descending.

When a vehicle is loaded, it can gain significant momentum and speed on a downhill slope. By downshifting, the driver can effectively use the engine's resistance to manage this momentum, helping to avoid overheating the brakes and reducing the risk of brake failure due to excessive use.

This practice not only enhances safety by providing better control of the vehicle but also helps in maintaining a consistent speed without relying solely on the service brakes. Other options suggest actions that would compromise control. For instance, accelerating could lead to an uncontrollable situation, turning off the engine would eliminate any power steering or braking assistance, and using cruise control can be dangerous on downhill grades as it may not adequately adjust for the changing terrain, allowing the vehicle to accelerate too quickly.