An ignition kill switch should be hidden or key-operated. A key-operated, on-and-off switch makes concealment unnecessary. Many circuits on late model computerised vehicles can be utilised. Early model vehicles require that the circuit to the coil be opened to kill the ignition. Whichever switch is chosen, it should have a 30-amp rating. Always make a solid connection, when installing a kill switch, to avoid any inadvertent engine cutoffs.
Drill a hole for the kill switch in the location you have predetermined. The switch can be mounted virtually anywhere there is a solid mounting, but it should be inconspicuous. Run a wire from the negative terminal on the coil through the firewall to the kill switch. Fold the wire to double its size and cut it at the fold with a crimping tool. You should have two equal lengths of wire extending from the coil through the firewall to the switch.
Strip the insulation off the coil end of the wires. Install a blue butt connector onto each of the wire ends and crimp them with the crimping tool. Cut the black negative wire to the coil 4 to 6 inches from the coil with the crimping tool. Strip the insulation off both these wire ends. Insert the coil end of the black negative wire into the butt connector on one of the wires leading to the switch. Crimp the butt connector and do the same with the second wire, attaching it to the other wire.
Strip the insulation off the two wires leading to the kill switch. Install a blue round post connector on both wires and crimp them tightly. Install the two wires in any order onto the back of the kill switch.
Push the kill switch through the hole drilled for the switch. Place the on-and-off label over the switch end followed by the retaining nut and tighten.
Determine the location for the kill switch. Drill a hole for the kill switch to prepare it for mounting.
Locate the ECM fuse. The main power fuse for the computer should be in the fuse and relay box under the hood on the driver's side fender well. If it is not there, look in the fuse block under the driver's side of the dash. The objective is to locate the fuse, remove the fuse block bolts or screws, turn the fuse block over and locate the wires to the fuse. There are usually only two screws or bolts securing the fuse block to the body. With the fuse located and the fuse block loose, place your finger on the fuse and locate the wires leading into the fuse from the rear of the fuse block. Cut either wire about 6 inches away from the fuse. Give yourself plenty of room to attach the wires.
Run two 14-gauge wires from the fuse wire that was just cut, through the firewall to the ignition kill switch. Connect one of the wires to the length of wire coming out of the fuse with a blue butt connector. Crimp it tightly with the crimping tool. Do the same for the other end of the wire that was cut.
Replace the fuse block and insert either the bolts or screws and tighten them. Connect the switch end of the wires with blue post-type connectors to the switch. Crimp the post terminals. Insert the switch through the hole, affix the on-and-off label, then reinstall the nut and tighten it.