How do a program the garage opener on a GM car?

To program the garage opener in a GM car, first ensure the vehicle is in park and turn on the ignition. Press and hold the two outer buttons on the HomeLink system until the indicator light changes from a slow blink to a rapid blink. Next, hold the garage door opener remote close to the HomeLink buttons and press the button you wish to program until the HomeLink light blinks slowly and then changes to a steady light. Finally, press the programmed HomeLink button to test the operation of your garage door.