2002 GMC Envoy Remote Programming Procedure:
WARNING: Before beginning remote learning mode, have with you all keyfob you will be using on the vehicle, including old ones you want to keep working. When you program the transmitter, all previous learned keyfobs will be eliminated from the memory. The other remotes will not be functional until you program the fobs again.
1. Shut all vehicle doors, have windows closed, wait for dome light to turn off.
2. Put key in ignition.
3. Press and Hold the power UNLOCK button on the driver’s door panel-don't let go until step 9.
4. Perform steps 5 through 8 in fairly rapid succession.
5. Switch the ignition switch to the ON position (as far as you can go WITHOUT cranking the engine).
6. Flip the ignition switch to the OFF position.
7. Flip the ignition switch to the ON position.
8. Switch the ignition switch to the OFF position.
9. Release the power unlock button on the door panel. The car will lock and unlock the doors automatically.
10. Hold down the LOCK and UNLOCK buttons on the transmitter simultaneously until the door locks lock and unlock. This step may take up to Half a minute.
11. Repeat step 10 for each additional fob(including any existing transmitters).
12. Switch the ignition switch to the ON position in order to depart the keyfob learning method.