Section 4 (Engine Controls - Tests W/Codes): Summary
WARNING: This page is about a different car, the 1994 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
If service Code 55 (pass code) is present, but driveability problem still exists, attempt to determine which EEC system is malfunctioning. After determining system, perform appropriate CIRCUIT TEST. See EEC DIAGNOSIS BY SYMPTOM table.