My mom's 06 Lucerne with the 3.8 V6 has a perplexing electrical issue. Every 3 to 5 run cycles, the car will just go dead when you try to start it. Every other time, it starts and runs just fine. The battery holds a 12 volt charge and the cables still look to be brand new and I see no corrosion whatsoever. Also, when the car goes dead, you can't pull the key out of the ignition and the only way I've been able to bring the car back to life is to jump start it on the positive post and a ground spot under the hood. I have a few theories of what could be going on, including the infamous Passlock system acting up, something called a battery current sensor, and maybe even the ignition switch, but I would feel better getting insight from someone who may have had this problem with their Lucerne or a tech who dealt with it. What was it and how did you fix it?