Erasing Channels
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
To erase programmed channels, press and hold the two outside buttons until the lights on the GDO transmitter begins to flash. Once the LEDs begin to flash, release both buttons; all learned codes are now erased.
Individual channels cannot be erased, but can be reprogrammed using the procedures above.