GMC Sierra Owners Manual
Hill and Mountain RoadsDriving and Operating / Driving Information / Hill and Mountain Roads
Driving on steep hills or through mountains is different than driving on flat or rolling terrain. Tips for driving in these conditions include:
• Keep the vehicle serviced and in good shape.
• Check all fluid levels and brakes, tires, cooling system, and transmission.
• Shift to a lower gear when going down steep or long hills.
If you do not shift down, the brakes could get so hot that they would not work well. You would then have poor braking or even none going down a hill. You could crash. Shift down to let the engine assist the brakes on a steep downhill slope.
Coasting downhill in N (Neutral) or with the ignition off is dangerous. The brakes will have to do all the work of slowing down and they could get so hot that they would not work well. You would then have poor braking or even none going down a hill. You could crash. Always have the engine running and the vehicle in gear when going downhill.
• Stay in your own lane. Do not swing wide or cut across the center of the road. Drive at speeds that let you stay in your own lane.
• Be alert on top of hills, something could be in your lane (stalled car, accident).
• Pay attention to special road signs (falling rocks area, winding roads, long grades, passing or no-passing zones) and take appropriate action.