What is the purpose of the "H/L" (High Lock) position on the transfer case?

The "H/L" (High Lock) position on the transfer case is specifically designed to improve traction when driving in challenging off-road conditions like mud, sand, and snow. Engaging this mode locks the front and rear axles together, distributing power evenly to all four wheels. This ensures that if one wheel slips, the opposite wheel receives power, helping maintain momentum and stability in low-traction scenarios.

This capability is crucial for HMMWVs, which are designed to operate in diverse and rugged environments where standard two-wheel drive would struggle. The other options do not accurately represent the function of the "H/L" position. For instance, increasing fuel efficiency or enhancing highway speed are more aligned with standard driving conditions rather than challenging terrains, while urban steering control is not impacted in the same way by this transfer case position.