Hummer 2003 H2 Owner's Manual page 289

Tow/haul may be turned off by pressing the button
again, at which time the indicator light on the instrument
panel will turn off. The vehicle will automatically turn
off tow/haul every time it is started.
Your vehicle is equipped
with a button on the
instrument panel, to the
right of the steering wheel,
which when pressed enables
tow/haul.
When the button is pressed,
this light on the instrument
panel will illuminate to
indicate that tow/haul has
been selected.
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 Combination
Weight Rating (GCWR). See "Weight of the Trailer"
later in this section. Tow/haul is most useful under the
following driving conditions:
D
When pulling a heavy trailer or a large or heavy load
through rolling terrain.
D
When pulling a heavy trailer or a large or heavy load
in stop and go traffic.
D
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.
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