Preliminary Testing

Before starting test procedures engine should be at operating temperature with oil temperature at 140°F (60°C). The Motronic system may be suspected when problems arise which are related to driveability, fuel economy or excess emissions. However, before beginning diagnosis ensure that all other systems are operating properly. Any engine system which would normally be checked in a vehicle not equipped with the Motronic system should be checked and approved before beginning Motronic testing.

When all other engine systems have been checked out, Motronic diagnosis may begin. Determine which component or area is the most probable source of performance difficulty and begin testing there. Many component failures may be traced to faults in the wiring circuit. Therefore, before beginning other diagnostic procedures, check the appropriate circuit for breaks or shorts and be sure that all electrical connections are clean and tight.