General Motor's GMC brand offered several vehicles for the 2003-model year. These vehicles include the Safari, Sonoma, Jimmy, Envoy, Yukon, Denali and Sierra. For said vehicles equipped with a factory-keyless entry system, programming a replacement or spare remote is the same; all vehicles use the same keyless-entry module. You may not be able to cross program remotes between vehicles. Make sure the remote you are trying to program is specifically made for your model.
Sit in the driver's seat and close the door. Insert the key into the ignition cylinder, but do not turn it. Press and hold "Unlock" on the driver's door switch. Continue to hold the buttons throughout the process, until otherwise instructed.
Turn the ignition to "On," but do not crank the engine. Turn it back to "Off," and then turn it to "On."
Turn the ignition to "Off." Let go of the "Unlock" button on the driver's door. The doors should lock then unlock. This lets you know that you have entered programming mode. If the doors do not lock then unlock, start over.
Press and hold "Unlock" and "Lock" on the keyless-entry remote. Wait for the door locks to lock then unlock. This takes up to 30 seconds.
After the doors lock and unlock, press and hold "Unlock" and "Lock" on the next remote, if you are programming multiple remotes. Wait for the doors to lock then unlock.
Turn the key to "On" when you are finished, and then turn it to "Off."
