Chevrolet 2006 TrailBlazer EXT Owner's Manual page 82

When a new vehicle is delivered, the dealer provides
the owner with a pair of identical keys and a key
code number.
2-4
This vehicle has one
double-sided key for the
ignition and door lock.
It will fit with either side up.
The key code number tells your dealer or a qualified
locksmith how to make extra keys. Keep this number in
a safe place. If you lose your keys, you'll be able to
have new ones made easily using this number.
Your selling dealer should also have this number.
Notice: If you ever lock your keys in your vehicle,
you may have to damage the vehicle to get in.
Be sure you have spare keys.
If you ever do get locked out of your vehicle, call the
GM Roadside Assistance Center. See Roadside
Assistance Program on page 7-6.
If your vehicle is equipped with the OnStar
an active subscription and you lock your keys inside
®
the vehicle, OnStar may be able to send a command to
unlock your vehicle. See OnStar
for more information.
®
system with
®
System on page 2-49