Cadillac XT5's Failed Start: Ignition Switch Nightmare

Had nearly identical starting issues with my 2015 Cadillac CTS. The engine start problems you describe match what I experienced, intermittent starting followed by rough running. While the ignition switch might seem like the culprit, in my case it turned out to be a failed fuel pump relay and a blown 20A fuse in the main fuse box. The dashboard lights would come on, but the engine would either fail to turn over or die immediately after starting. The repair involved replacing both the relay and fuse, plus cleaning the electrical connections. This was actually a serious issue since a faulty relay can leave you stranded without warning. The symptoms can mimic ignition switch failure, but car electronics have become quite complex in modern vehicles. Before replacing the ignition switch, have the fuel system electrical components tested, particularly the relay and fuse circuit. Your starting issue sounds very similar to what I experienced, and the fix was much simpler than replacing the entire ignition system. Worth mentioning that driving with these symptoms risks damaging other components due to improper fuel delivery. Getting this diagnosed properly is important for preventing cascade failures.

Thanks for sharing your experience with the CTS fuel system issue. I had a similar starting problem with my XT5 that turned out to be failing ignition coils and one bad starter motor. The symptoms matched exactly, engine would crank but either not start or die right away. Even after multiple tries with the ignition key, the engine would run really rough. Did you happen to track how much the fuel pump relay repair cost you? Just wondering if I got overcharged for my fix. Also, have you experienced any other starting issues since getting it repaired? My car has been running fine for 3 months now but still curious if I should watch out for anything specific.

Thanks for asking about the repair costs. After seeing the mechanic, the ignition switch problem was indeed resolved, but you are right to compare repair costs. The fuel pump relay and fuse replacement came to just 52€ total, including labor. This was mainly due to the quick diagnostic process and the fuse being defective. Your starter motor and ignition coil issues sound more complex than what I dealt with, which explains the higher repair cost. With modern cars, the ignition system has multiple components that can fail independently. Since the repair 8 months ago, my engine start sequence has been flawless. No more problems with the ignition key or rough running. However, its good practice to listen for any unusual sounds when starting the car. If the engine hesitates or sounds rough during start, it could indicate developing issues with the ignition coils or starter motor. The mechanic also recommended checking the fuses every 6 months as preventive maintenance, which might be worth doing on your XT5 too.

After getting the car key to turn but having no luck with proper starts, I finally took it to a certified mechanic last week. Turned out I had both failing ignition coils and a bad starter motor causing the starting issues. The diagnosis took about an hour since they had to test multiple car electronics components. The repair cost came to 430€ total, pretty steep but worth it since the car starts perfectly now. They showed me the worn starter motor and explained how bad ignition coils were causing the rough running. The dashboard lights had been trying to warn me with that check engine light, but I ignored it too long. The mechanic also cleaned all the electrical connections and checked the entire ignition system while they had it apart. Been driving it for a week now with zero starting problems. The engine fires up instantly when I turn the key and runs smooth. Really glad I got it properly diagnosed instead of continuing to drive it in that condition. Main lesson learned: dont ignore starting issues hoping they will fix themselves. Getting stranded would have been much worse than the repair bill.