When going down a steep hill, you should

If you keep applying the brakes to control your speed on a steep downgrade, the brakes will fade (lose their effectiveness). Instead, release the gas pedal and shift into a lower gear (even with an automatic transmission). When the throttle is closed, a partial vacuum is created in the engine's intake and cylinders that generates a braking effect to slow the vehicle. This is known as engine braking. The lower the gear, the greater the engine braking effect. Apply the brakes only when engine braking is insufficient or you want to stop. Never coast in neutral or with your foot on the clutch.