Last night I left the headlights on in my 2003 Cavalier. Naturally, this morning it wouldn't start. I hooked it up with jumpers to another car and gave it about 10 or so minutes, but still didn't have any power, radio, ignition, lights, all nothing. I put a multimeter to the battery and got 0v. Figuring the battery to just be dead I went to the parts store and got it tested, where it again showed 0 so dead battery. I bought a new one, installed it, and the lights popped on, radio even kicked back on. But when I went to turn the key to test it I only got a single sort of click along with the sound of what I think were pumps, or electric motors. The brake pedal was also staying stiff. I turned the key back off, then on again and this time only the pumps or motors or whatever they were, no click. Took the key out put the multimeter onto the battery again and got a good 13v. Went again to start it and got the same click as the first try, pumps, but no ignition. Next turn was just pumps. My googleing brought up a few mentions that talked about an immobilizer. This car doesnt have an alarm, and I wasnt aware of any anti-theft systems, but maybe this is standard? Any advice on how to get this car to start up again would be appreciated.
If it makes a difference, this car has the 2.2 L DOHC Ecotec SFI L4 engine.

 

Bad battery wires, bad connection on battery terminals.

 

Didn't notice how bad those battery connectors were. Gave it a couple rounds of baking soda and water, and it's back up and running again. Thanks for the advice.

 

You are welcome!