Chevrolet 2007 TrailBlazer Owner's Manua page 155

Read the instructions completely before attempting
to program the transmitter. Because of the steps
involved, it may be helpful to have another person
available to assist you in programming the
transmitter.
Be sure to keep the original remote control
transmitter for use in other vehicles, as well as, for
future programming. You only need the original
remote control transmitter for Fixed Code
programming. It is also recommended that upon the
sale or lease termination of the vehicle, the
programmed buttons should be erased for security
purposes. See "Erasing Universal Home Remote
Buttons" later in this section.
When programming a garage door, it is advised to
park outside of the garage. Be sure that people and
objects are clear of the garage door or security
device you are programming.
Programming Universal Home
Remote — Rolling Code
Most garage door openers sold after 1996 are
Rolling Code units.
Programming a garage door opener involves
time-sensitive actions, so read the entire procedure
before you begin. If you do not follow these
actions, the device will time out and you will have
to repeat the procedure.
Follow these steps to program up to three devices:
1. From inside the vehicle, press the two outside
buttons at the same time for one to two seconds,
and immediately release them.
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