Aston Martin DB 9 2010 Manual page 26

The HomeLink system operates the garage door opener (or other
device) in exactly the same way as the original remote control.
When you have programmed the
HomeLink system, press the
appropriate button 1, 2, or 3 on the
control panel to operate the garage
door opener.
The LED will come ON when the
button on the control panel is
pressed.
For convenience, the original
remote control of the device may
also be used at any time.
2.16
In the case of a standard code, the HomeLink LED is constantly ON
throughout the transmission process. For use with compatible
systems, no further action is necessary.
If HomeLink now does not operate the garage door opener (or other
device), this may be because the original remote control has a rolling
code feature. Refer to 'Rolling Code Synchronization'.
Rolling Code Synchronization
Check, by going through the following steps, whether or not the
garage door opener (or other device) is equipped with a rolling code
feature.
• Look in the garage door opener manual for clarification
• The remote control apparently programs HomeLink but
HomeLink does not operate the garage door opener
• Press and hold down the programmed HomeLink button
With a rolling code system, the HomeLink LED flashes quickly for
a short time and then stays ON constantly for two seconds. This
pattern repeats itself for up to 20 seconds.
If HomeLink was programmed with a rolling code system, then after
the end of the programming period it must be synchronized with this
system again before it will function properly.
Follow the instructions below for Rolling Code Synchronization (the
procedure will take less time with a second person to help).