I purchased a 2004 CTS 5 weeks ago and have gotten very little use from it. I have had this “no-start” issue over seven times now and no one can figure out exactly what the problem is. For some reason the theft deterrent module prevents the vehicle from starting. When problem first started, I had the module replaced with a new part. The first time starting the car after leaving the dealer, the problem still occurred. I had the vehicles entire systems put on the diagnostic testers and they could come up with nothing. The new part was tested to see if defected. They erased all codes and reset them, including both keys, etc. and they were confident this would do the trick. Once again, upon leaving the dealership, I stopped at the grocery and then the car would not start. I am so frustrated, as well as the dealer. I am aware of the method to start the car in the meantime…without having it towed, though it cannot be relied on because it does run the battery down and you can get stuck somewhere without power to use this trick to bypass the security theft deterrent system, but it is…turn the ignition key to “accessory” position just before start (do not turn all the way as if to start) engine and leave there for at least 10 minutes, turn off and repeat for second time, turn off and repeat third time, after you have done this three times, it should start. The second time I had to do this, it ran the battery dead and I had to install a semi-permanent chargery on to the battery that I can just plug into a socket in my garage. In the meantime, no one can figure out what is wrong and I am unable to use the car. Have you had any success with your problem? Can anyone else shed light on this? HELP!!