If you can duplicate the symptom, compare it to a ‘‘similar known-good vehicle.'' Only use a vehicle of the same model, same year, same trim, and same software version. If you can duplicate the symptom in the similar known-good vehicle, then it is a characteristic of the system.
When the symptom can be duplicated, follow the self-diagnostic procedures and the appropriate troubleshooting procedures.
When the symptom does not reappear or only reappears intermittently, ask the customer about the conditions when the symptom occured.
-
Try to establish if outside interference may be the cause.
-
Try to duplicate the symptom under the same conditions the customer was experiencing.
-
Vibration, temperature extremes, and moisture (dew, humidity) are factors that are difficult to duplicate.
-
Inspect the vehicle for after-market electronic devices (vehicle locators, radar detector amps, etc.) that may be hidden.