GMC 2009 Sierra 1500 Crew Cab Owner's Manual page 174

4. Immediately, within one second, release the button
when the garage door moves. The indicator light
will blink rapidly until programming is complete.
5. Press and release the same button again.
The garage door should move, confirming
that programming is successful and complete.
To program another Rolling Code device such as an
additional garage door opener, a security device,
or home automation device, repeat Steps 1 through 5,
choosing a different function button in Step 3 than
what was used for the garage door opener.
If these instructions do not work, the garage door
opener is probably a Fixed Code unit. Follow the
Programming instructions that follow for a Fixed Code
garage door opener.
Programming Universal Home
Remote — Fixed Code
For questions or help programming the Universal
Home Remote System, call 1-866-572-2728 or go to
learcar2u.com.
Most garage door openers sold before 1996 are Fixed
Code units.
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Programming a garage door opener involves
time-sensitive actions, so read the entire procedure
before starting. Otherwise, the device will time out and
the procedure will have to be repeated.
To program up to three devices:
1. To verify that the garage door opener is a Fixed
Code unit, remove the battery cover on the hand
held transmitter supplied by the manufacturer of
the garage door opener motor. If there are a row
of dip switches similar to the graphic above,
the garage door opener is a Fixed Code unit.