- Important Preliminary Checks

Important Preliminary Checks Before Starting

Before using Diagnosis By Symptom, you should have performed the Powertrain On-Board Diagnostic System Check and verify all of the following are true: Testing and Inspection

^ The PCM and Malfunction Indicator Lamp (MIL) (Service Engine Soon) are operating correctly.

^ There are no DTC(s) stored.

^ Scan data is within normal operating range, Refer To Typical Scan Tool Data values.

^ Verify the customer complaint, and locate the correct symptom. Check the items indicated under that symptom.