GMC 1999 Envoy Owner's Manual page 92

Press the side of the switch with the down arrow to
lower the window.
Press the side of the switch with the up arrow to raise
the window.
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Express Down Window
The driver's window switch has an express
feature that allows you to lower it without holding the
window switch. Hold the driver's window switch down
for more than half a second to activate the express
feature. Lightly tap the switch to open the window
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slightly. The express down feature can be interrupted at
any time by pressing the up arrow end of the switch.
Lockout Switch
Your vehicle has a lockout feature to prevent passengers
from operating power windows. It is located on the
driver's door. Press LOCK to activate this feature. Press
NORM to have the windows return to normal operation.
Horn
To sound the horn, press the center of the steering
wheel pad.
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