The programming of a remote keyless transmitter depends on the model of the vehicle, but in most cases, it requires a series of tasks such as locking and unlocking the door and turning the key in the ignition. The car should not start during the process of programming.
If programming a GM vehicle, such as a Chevrolet or GMC, start the process by closing all of the vehicle doors and placing the key into the ignition. Hold down the unlock button on the driver's side door, and keep holding it.
Turn the ignition to the on position, which is as far as the key goes without turning the car on, and then switch it to the off position. Repeat this one more time, from on to off, in rapid succession. Release the finger from the unlock button on the door panel. If the process was successful, the vehicle automatically locks and unlocks the doors. This confirms that it is ready for the programming.
To finish the programming process, hold down both the lock and unlock buttons on the transmitter until the door locks open then lock. This can take 30 seconds to complete. Turn the ignition to the on position to exit programming mode, and then repeat this process for other remote keyless transmitters.