Brakes are meant to slow down and stop a car. But when it comes to driving a car with an automatic transmission down a mountain, using your brakes alone may not be enough. Plus, it wears down your brakes and reduces their usefulness. That's why it's important to use more than your brakes when you're driving down a steep slope.
Remove your foot from the car's accelerator at the top of the mountain before you start down. If you have the cruise control on, shut it off. Turn it off with the hand control or tap the car's brakes gently to disengage your cruise control.
Hold onto the steering wheel firmly to help maintain control of the car. If you're already moving slowly, shift the automatic transmission into low or second gear. By doing this "engine braking," the transmission will help to slow your car down.
If you're moving faster than about 30 to 35 mph, or whatever speed feels safe for the road you're travelling, pump the car brakes gently to reduce your speed. If you have a lower gear, shift into it, if necessary, to help keep your speed down.
Gently pump your brakes from time to time to help the engine stay at a reduced speed. Otherwise, if the car is in second gear going down a mountain, you'll pick up speed, and the transmission will kick into drive.
Move the gear lever back to "Drive" once you reach the bottom of the mountain to proceed at your regular speed.
Before you drive your car down a mountain, make sure the brakes are in good condition.
Unless you drive down a mountain that has little traffic, or slow-moving traffic, or has a curvy road, you won't want to shift into first, the lowest gear. The maximum speed of this gear is approximately 15 to 20 mph. Never shift your car into "Neutral," or you'll freewheel down the mountain faster than you want to go. Never shift an automatic transmission into "Park" as a means to slow down when you drive down a mountain. Your car will likely jerk and make terrible noises. Even worse, you'll ruin the transmission.