Just for grins, if you think the parking brake diagnosis is simple, you would not believe how many sensors are involved. Check this out:
https://www.foexplorer.com/ford_exp..._operation_and_component_description-547.html
If you bother to look, you'll see there are literally scores of sensors, microswitches, electric motors, computers and canbus messages that could cause a problem. Makes one wish for a manually activated parking brake.