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. Check all basic engine components and functions before beginning Motronic system diagnosis and testing.

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