GMC 2010 Yukon XL Denali Owner's Manual page 147

To arm the theft-deterrent system:
1. Open the door.
2. Lock the door with the Remote Keyless Entry
(RKE) transmitter or the power door lock switch.
The security light will come on to inform the driver
the system is arming. If a door is open when the
doors are locked, the security light will flash.
If the delayed locking feature is turned on, the
theft deterrent system will not start the arming
process until the last door is closed and the delay
timer has expired. See Delayed Locking on
page 3 10.
3. Close all doors. The security light should go off
after about 30 seconds. The alarm is not armed
until the security light goes off.
If a locked driver door is opened without using the RKE
transmitter, a ten second pre-alarm will occur. The horn
will chirp and the lights will flash. If the key is not placed
in the ignition and turned to START or the door is not
unlocked by pressing the unlock button on the RKE
transmitter during the ten second pre-alarm, the alarm
will go off. Your vehicle's headlamps will flash and the
horn will sound for about 30 seconds, then will turn off
to save the battery power.
The theft-deterrent system will not activate if the doors
are locked with the vehicle's key or the manual door
lock. It activates only if you use the power door lock
switch with the door open or the RKE transmitter.
You should also remember that you can start your
vehicle with the correct ignition key if the alarm has
been set off.
To avoid setting off the alarm by accident:
If you do not want to activate the theft-deterrent
system, the vehicle should be locked with the door
key after the doors are closed.
Always unlock the doors with the RKE transmitter.
Unlocking a door any other way will set off the
alarm if it is armed.
If you set off the alarm by accident, press unlock on the
RKE transmitter or place the key in the ignition and turn
it to START to turn off the alarm. The alarm will not stop
if you try to unlock a door any other way.
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