GMC Chevrolet Tahoe 2003 Manual page 107

The following instructions tell you how to change the
automatic door lock mode. Choose one of the three
programming options listed above before entering the
program mode. To enter the program mode, do the
following:
1. Begin with the ignition off. Then pull the turn
signal/multifunction lever toward you and hold
it there while you perform the next step.
2. Turn the key to RUN then back to LOCK twice.
Then, with the key in LOCK, release the turn
signal/multifunction lever. Once you do this, the
doors will lock and unlock, the horn will chirp twice,
and a 30-second timer will begin. You are now
ready to program the automatic door lock feature.
3. Press the door lock switch once. You will hear one,
two, or three chimes. The number of chimes tells
you which lock mode is currently selected. Continue
to press the door lock switch until the number of
chimes that you hear matches the number of
the mode that you want. If you take longer than 30
seconds, the locks will automatically lock and
unlock and the horn will chirp twice to indicate that
you have left the program mode. If this occurs,
you can repeat the procedure beginning with Step 1
to re-enter the programming mode.
You can exit the program mode any time by turning the
ignition to RUN (the doors will automatically lock and
unlock and the horn will chirp twice to indicate that you
are leaving the program mode). If the lock/unlock
switches are not pressed while in the programming mode,
the current automatic settings will not be modified.
See your dealer for more information.
Programmable Unlocking Feature
The following is the list of available programming options:
Mode 1: Driver's door unlocks when the transmission is
shifted into PARK (P)(automatic transmission vehicles
only).
Mode 2: All doors unlock when the transmission is
shifted into PARK (P)(automatic transmission vehicles
only). This is the mode that is pre-programmed in
the factory for your vehicle.
Mode 3: All doors unlock when the key is removed
from the ignition This is the mode that is
pre-programmed in the factory for manual transmission
vehicles.
Mode 4: No automatic door unlock.
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