First time you will have to program all your fobs. Al mismo tiempo, the instruction were easily printed in a readable format, which i now keep with my owners and maintenance manual. My original fob did not work after programming the new ones, so i just went through the instructions again and voila. I have three working units as another mention sorta wished it. The oem part number on the back, so it could be easily referenced if needed. Later works with our 2000 chevy s10 zr2 for a while there i never thought the truck was going into programming mode, because the doors did not go into the lock to unlock cycle. After releasing the unlock switch on the driver’s side, i found only one thing different than the programming instructions, and maybe this will help someone else. The instructions tell you to enter the vehicle and make sure all the doors and windows are closed. próximo, it tells you to hold down unlock, switch on the driver’s side and turn the ignition to on and off twice and let go of the unlock switch and wait for the locks to cycle from lock to unlock, which lets you know. You are in programming mode.