Power Steering Pressure Switch (PSPS)
WARNING: This page is about a different car, the 1995 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.
Faulty PSPS or circuit should set a diagnostic trouble code. See QUICK TEST in TESTS W/CODES - EEC-IV (3.0L) article. If diagnostic trouble code has not been set, see CIRCUIT TEST FF in TESTS W/CODES - EEC-IV (3.0L) article for testing.