Driving On Grades; Parking On Hills - GMC 2010 Canyon Crew Cab Owner's Manual

Driving On Grades

Reduce speed and shift to a lower gear before starting
down a long or steep downgrade. If the transmission is
not shifted down, the brakes might have to be used so
much that they would get hot and no longer work well.
Vehicles with automatic transmissions can tow in
D (Drive), but you may want to shift to a lower gear
selection if the transmission shifts too often (e.g., under
heavy loads and/or hilly conditions). If the vehicle has
a manual transmission it is better not to use the
highest gear.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If the engine is
turned off immediately after towing at high altitude on
steep uphill grades, the vehicle may show signs similar to
engine overheating. To avoid this, let the engine run while
5-58
parked, preferably on level ground, with an automatic
transmission in P (Park) or a manual transmission in
N (Neutral) with the parking brake applied, for a
few minutes before turning the engine off. If the overheat
warning comes on, see Engine Overheating on page 6-35.

Parking on Hills

WARNING:
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Parking the vehicle on a hill with the trailer
attached can be dangerous. If something goes
wrong, the rig could start to move. People can be
injured, and both the vehicle and the trailer can be
damaged. When possible, always park the rig on a
flat surface.