GMC Yukon 2012 Owner's Manual page 285

If the vehicle stalls on a hill:
1. Apply the brakes to stop the
vehicle, and then apply the
parking brake.
2. Shift into P (Park) and then
restart the engine.
If driving uphill when the
vehicle stalls, shift to
R (Reverse), release the
parking brake, and back
straight down.
Never try to turn the vehicle
around. If the hill is steep
enough to stall the vehicle,
it is steep enough to cause
it to roll over.
If you cannot make it up
the hill, back straight
down the hill.
Never back down a hill
in N (Neutral) using only
the brake.
The vehicle can roll
backward quickly and you
could lose control.
If driving downhill when the
vehicle stalls, shift to a
lower gear, release the
parking brake, and drive
straight down the hill.
3. If the vehicle cannot be restarted
after stalling, set the parking
brake, shift an automatic
transmission into P (Park), and
turn the vehicle off.
3.1. Leave the vehicle and
seek help.
3.2. Stay clear of the path the
vehicle would take if it
rolled downhill.
Avoid turns that take the vehicle
across the incline of the hill.
A hill that can be driven straight
up or down might be too steep to
drive across. Driving across an
incline puts more weight on the
downhill wheels which could
cause a downhill slide or a
rollover.
Driving and Operating
Surface conditions can be a
problem. Loose gravel, muddy
spots, or even wet grass can
cause the tires to slip sideways,
downhill. If the vehicle slips
sideways, it can hit something
that will trip it a rock, a
rut, etc. and roll over.
Hidden obstacles can make the
steepness of the incline more
severe. If a rock is driven across
with the uphill wheels, or if the
downhill wheels drop into a rut
or depression, the vehicle can
tilt even more.
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