Others, even Chrysler, used seperate solenoid relays at various times. Its just easiest to get one at the parts store by looking up a Ford.
:)
It keeps the big cable to the starter off. Only when the key switch goes to start does the solenoid get the power to connect it to the battery cable.
This is basically
@crackedback's schematic - I just moved things around so it was easier for me to read.
View attachment 1715844667
