GMC Denali 2004 Owner's Manual page 234

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(4 Wheel Steer tow mode): When towing a
trailer the 4 wheel steer tow mode provides enhanced
stability allowing the trailer to follow the path of the
tow vehicle more closely, especially during lane
changes.
In this mode the system operates much like the 4 mode,
but is enhanced for trailer towing. It is recommended
for all types and weights of trailers.
To engage the 4 wheel steer tow mode, press the 4
Wheel Steer button until the 4 and tow indicators light up
on the instrument panel. If the tow indicator is flashing
you will have to center the steering wheel by turning it to
the left or right. While in the 4 wheel steer tow mode,
it is possible the steering wheel may be slightly off
center. For more information, see Towing a Trailer on
page 4-58 .
4-14
Car Washes for
QUADRASTEER™ Equipped Vehicles
Notice: Because your vehicle has a wider rear track
a small number of older car washes may be too
narrow for your vehicle. Conveyor systems on some
automatic car washes may damage your vehicle.
Only use conveyor system car washes with 13-inch
(33 cm) wide conveyor rails and/or stationary
washes with at least 82 inches (208 cm) between the
rails. Before using the car wash check with the
manager.