What my car did when I needed a new battery, ignition coil, and crankshaft position sensor.
2003 Cadillac CTS 103,000 mi. One day, I went to the store. When I got out, my car would crank, but not start. Hmmm. Unplugged battery, plugged it back, same thing. Walked to the gas station got two gallons, put them in, started right up because the car was cool again. Later found that it was in fact the crankshaft position sensor, $52 at Class A Auto Parts, since my car would only start when it was cool. This is located just above the oil filter under the car, held in by a single bolt. Its a pain in the butt to get out. The harness is located on the top of the engine in the back center. Cylinders 2, 4, and 6 were misfiring, and my battery would be dead everytime I got into the car. This was driverside ignition coil, $120 at Autozone. They were able to tell me this beacause CHECK ENGINE light was on. Just move the powersteering tank and rubber engine cover, and its pretty easy to switch out. After I replaced the coil, my battery was dead. I tried to jump it, but it wouldn't even crank, even though the battery volts on the nav screen read 13.3. This was the battery. It was almost 7 years old, and if its dead enough it won't even take a jump, why, I don't know. I was stupid and paid $165 for a new one from Cadillac when I learned later that a diehard 78 series would work fine, just move 1" to the right. I just wanted to help you guys out since the CHECK ENGINE light doesnt come on when the crankshaft position sensor or the battery go bad. Its funny too, because all of these things happened at the same time. Car runs great now, I hope this helped, GOOD LUCK!!
