[Terry,OH]

The wiring diagram is deceiving. If you look in the owners reference book you will find the light switch has an off position in the center of it's three positions. In the off position the battery is just connected to the stop light circuit. Battery power does not go to the glove box or instrument lights.

With the light switch rotated one position C.W from OFF the battery is connected to the parking lights, instrument and tail lights as well as the stop light circuit.

Rotating the switch one position C.C.W. from OFF and then the headlight circuit, instrument, tail lights, as well as the stop light circuit have battery power.
Ford did not know how to draw the light switch using todays standards.