The ignition switch on a Ford F100 is held to the steering column with a retaining tab inside the steering column. An access hole in the column allows you to easily remove the switch and cylinder assembly without removing the entire steering wheel, as you must do on some vehicles. If your ignition switch fails, you may still be able to turn the ignition key, but you won't be able to start the vehicle. When this happens, you need to know how to replace the switch.
Turn the ignition key to the "II' position.
Slide the punch pin into the hole on the underside of the steering column. The hole is positioned directly under the ignition switch and cylinder assembly.
Pull the switch out with the key and remove the punch pin.
Insert the new switch with the key turned to the "II" position until the switch locks into the steering column.
Turn the key to the "Off" position.