GMC 2009 Savana - Manual (Page 238)

Tow/Haul is designed to be most effective when the
vehicle and trailer combined weight is at least 75 percent
of the vehicle’s Gross Combined Weight Rating
(GCWR). See “Weight of the Trailer” later in the section.
Tow/Haul is most useful under the following driving
conditions:
• When pulling a heavy trailer or a large or heavy
load through rolling terrain.
• When pulling a heavy trailer or a large or heavy
load in stop and go traffic.
• When pulling a heavy trailer or a large or heavy
load in busy parking lots where improved low
speed control of the vehicle is desired.
Operating the vehicle in Tow/Haul when lightly loaded
or with no trailer at all will not cause damage. However,
there is no benefit to the selection of Tow/Haul when
the vehicle is unloaded. Such a selection when unloaded
may result in unpleasant engine and transmission
driving characteristics and reduced fuel economy.
Tow/Haul is recommended only when pulling a heavy
trailer or a large or heavy load.
Trailer Brakes
A loaded trailer that weighs more than 1,500 lbs (680 kg)
needs to have its own brake system that is adequate for
the weight of the trailer. Be sure to read and follow the
instructions for the trailer brakes so they are installed,
adjusted and maintained properly.
Driving with a Trailer
{ CAUTION:
When towing a trailer, exhaust gases may collect at
the rear of the vehicle and enter if the liftgate,
trunk/hatch, or rear-most window is open.
Engine exhaust contains carbon monoxide (CO)
which cannot be seen or smelled. It can cause
unconsciousness and even death.
To maximize safety when towing a trailer:
• Have the exhaust system inspected for
leaks and make necessary repairs before
starting a trip.
• Never drive with the liftgate, trunk/hatch, or
rear-most window open.
• Fully open the air outlets on or under the
instrument panel.
• Adjust the Climate Control system to a setting
that brings in only outside air and set the fan
speed to the highest setting. See Climate
Control System in the Index.
For more information about carbon monoxide, see
Engine Exhaust on page 2-30
4-36