GMC 1993 Safari Owner's Manual page 146

Comfort Confm/s & Audio Systems
You can preset 3 more stations on each band by pushing a pair of buttons
next to each other at the same time. Just:
1. Tune in the station.
2. Push SET. (SET will be displayed.)
3. Within 5 seconds, push
two buttons next to each other at the same
time. Whenever you push that pair of buttons, the preset station will
return.
Repeat these steps for each pair of buttons.
Scan Button
When you push this, the radio will go to the next station and stay there
a
few seconds. Then it will go to the next station and pause, and keep doing
that. Press SCAN again to stop scanning.
Seek Button
This chooses stations also, but it doesn't keep moving as
SCAN does. When
you push SEEK, the radio goes to the next station and stays there.
Clock
To set the clock, just:
1. Push SET. (SET will be displayed.)
2. Within 5 seconds, push and hold SCAN until the correct hour appears.
3. Press and hold SEEK until the correct minute appears.
To display the clock with the ignition off, push the upper knob. The time will
be displayed for a few seconds.
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