GMC 1998 Sonoma Owner's Manual page 96

Swing-Out Windows (Extended Cab) Sliding Rear Window (If Equipped)
When you close the window, be sure the latch catches.
Squeeze the latch in the center of the window and slide
the glass to open it.
When you close the window, be sure the latch catches.
Horn
Press the steering wheel pad to sound the horn.
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