2008 GMC Sierra 1500 Pickup Owner's Manual - Page 97

If the engine still does not start, and the key appears to be undamaged, try another ignition key. At this time, you may also want to check the fuse, see Fuses and Circuit Breakers on page 5-108. If the engine still does not start with the other key, your vehicle needs service. If your vehicle does start, the first key may be faulty. See your dealer/retailer who can service the PASS-Key® III+ to have a new key made. In an emergency, contact Roadside Assistance. It is possible for the PASS-Key® III+ decoder to learn the transponder value of a new or replacement key. Up to 10 keys may be programmed for the vehicle. The following procedure is for programming additional keys only. If all the currently programmed keys are lost or do not operate, you must see your dealer/retailer or a locksmith who can service PASS-Key® III+ to have keys made and programmed to the system. See your dealer/retailer or a locksmith who can service PASS-Key® III+ to get a new key blank that is cut exactly as the ignition key that operates the system. To program the new additional key: 1. Verify that the new key has a 1 stamped on it. 2. Insert the original, already programmed, key in the ignition and start the engine. If the engine will not start, see your dealer/retailer for service. 3. After the engine has started, turn the key to LOCK/OFF, and remove the key. 4. Insert the new key to be programmed and turn it to the ON/RUN position within five seconds of turning the ignition to the LOCK/OFF position in Step 3. The security light will turn off once the key has been programmed. 5. Repeat Steps 1 through 4 if additional keys are to be programmed. If you lose or damage your PASS-Key® III+ key, see your dealer/retailer or a locksmith who can service PASS-Key® III+ to have a new key made. Do not leave the key or device that disarms or deactivates the theft deterrent system in the vehicle. 2-21