How Do I Tell Which EEC System I Have?

- Federal models over 8600 lbs. Gross Vehicle Weight (GVW) are equipped with Electronic Engine Control (EEC) IV, which is an On Board Diagnosis (OBD) I system. Diagnostic Trouble Codes (DTCs) are accessed using the familiar 6 pin data link connector and single pin Self-Test Input (STI) connector. These are mounted at the left front of the engine compartment. Conventional three digit DTCs are used. This is a multiport fuel injection system.

- All California models, and Federal models under 8600 lbs. GVW are equipped with EEC V, which is an OBD II system. Diagnostic trouble codes are accessed using a special 16 pin OBD II data link connector mounted below the instrument panel. Four digit OBD II "P" codes are used. This application has sequential fuel injection, and a mass airflow sensor is used.

- For more information, see POWERTRAIN MANAGEMENT/APPLICATION AND I.D. Application and ID