How do you program a key Cadillac CTS 2008?

To program a key for a 2008 Cadillac CTS, you typically need to have both the new key and an existing programmed key. Insert the existing key into the ignition and turn it to the "On" position without starting the engine. After 10 minutes, turn the key back to the "Off" position, then repeat this process two more times for a total of three cycles. Finally, insert the new key and turn it to the "On" position for about 10 minutes to program it. If you don't have an existing key, you may need to visit a dealership or a locksmith with the appropriate equipment.