This how-to will walk you through installing a starter kill relay in a cobalt.
1 - 5 post relay
1 - on/off switch
2 strips of about 3-4ft of wire, preferably 14g to match stock (wire length depends on where you want to mount your relay)
basic electrical tools (wire strippers, test light, soldering iron, electrical tape, possibly crimps and connectors for the relay if yours isnt prewired)
Locate the starter wire under the hood. Its a light purple/violet color and is 14g so its thicker than the rest. Find it, test it. It will be negative at rest and positive when cranking. Once you know thats the right wire, cut it.
Feed your 2 lengths of wire threw the firewall to the start wire. If the wires are identical, mark one with a marker on each end so they can be identified later. Save these wires for later.
Open drivers right kickpannel (easiest to remove the white mount as well) Locate the large connector under the radio area, find an ignition wire. It is the only yellow wire that I could see on mine, but test it. Its rather skinny, maybe 24g wire. Connect this ignition wire to one of the wires going through the firewall. I labelled mine previously with a (+) since IGN is 12v+.
Wire and mount your switch where you want it. Note that it will be a ground wire trigger so you have a great deal of options of where you want it. Ground one side and run the other side to the 2nd wire going through the firewall.
No Pictures, mines controlled by may alarm, not a switch
Connect your relay to your cut starter wire using pins 87a and 30. I put 30 on the fusebox side and 87a on the engine side.
Wire the relay!
Pin 87 is unused
Pin 87a is youre engine side starter wire
Pin 30 is youre fusebox side starter wire
Pin 86 is youre ignition wire
Pin 85 is youre switch/trigger wire
See google for a pic
Clean everything up and test your new starter kill. Engaging the switch will "cut" youre starter wire making it impossible to start the car. Flip the switch off and you get a connected wire at rest and the car starts.
****NOTE**** You MUST have the relay close to the starter wire or there wont be enough power to turn over the starter. Trust me, I had to redo mine when I had the relay inside the car.