The ignition switch on a Ford Thunderbird unlocks the ignition lock cylinder and sends an electrical signal to the starter motor so that the Thunderbird's engine can start. Over time, the ignition switch can fail. Usually, this is due to the tumblers inside the ignition lock jamming. When this happens, you'll need to replace the switch. Once you've removed the old switch, you have to follow a special procedure to install the new one.
Hold the new ignition cylinder in your left hand and slide the ignition key into the ignition cylinder. The switch is on the backside of the cylinder housing on the Thunderbird.
Turn the ignition key clockwise two positions on the cylinder. The lock should click twice, once for each position.
Insert the ignition cylinder and switch into the steering column in the switch and cylinder input.
Push the cylinder and switch all the way into the column until the ignition switch locks into position on the column.
Turn the ignition key to the "off" position and remove the key.
