GMC Chevrolet Tahoe 2003 Manual page 120

Adjustable Throttle and Brake Pedal
If your vehicle is equipped with this feature, you can
change the position of the throttle and brake pedals.
This feature is designed for shorter drivers, since
the pedals can not move farther away from the standard
position, but can move toward the driver for better
pedal reach.
The vehicle must be in PARK (P) for this feature to
operate.
Press the arrow at the end of the switch closest to you
to move the pedals closer to your body. Press the
arrow at the far end of the switch to move the pedals
away from your body.
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The switch used to adjust
the pedals is located on
the driver's side door
panel.
Engine Coolant Heater
At temperatures above 32°F (0°C), use of the coolant
heater is not required.
In very cold weather, 0°F
(−18°C) or colder, the
engine coolant heater can
help. You'll get easier
starting and better
fuel economy during
engine warm-up. Usually,
the coolant heater
should be plugged in a
minimum of four hours
prior to starting your
vehicle.