Although manual code retrieval is useful as a 'quick-and-dirty' method of accessing codes without sophisticated equipment, manual code retrieval is...

Although manual code retrieval is useful as a 'quick-and-dirty' method of accessing codes without sophisticated equipment, manual code retrieval is limited, slow and prone to error. What is the preferred method of clearing codes generated by mid-1980s systems?

Manual code retrieval is useful as a 'quick-and-dirty' method of accessing codes without sophisticated equipment.
Manual code retrieval is limited, slow and prone to error.
Removing a battery lead or the ECM multi-plug.
Using a jumper lead to bridge certain terminals in the SD connector.
Clearing codes with an FCR.
Clearing codes with the aid of a personal computer (PC).