ECM/PCM Diagnosis

OVERVIEW
After the visual inspection is complete, the Powertrain OBD System Check should be performed. This Powertrain System Check will provide direction for diagnosis of the following:

^ PCM inoperative or damaged, no PCM data or SERVICE ENGINE SOON MIL inoperative.
^ PCM DTC(s).
^ Fuel System Rich or Lean.
^ Customer Complaint Driveability Symptoms. The Powertrain OBD System Check is designed as a Master table for driveability and emissions system diagnosis. The System Check should always be used as the starting point for all Powertrain diagnosis. Refer to OBD System Check. Testing and Inspection

The Powertrain OBD System Check is an organized approach for identifying a problem. Driver Comments normally fall into one of the following areas:

^ Steady SERVICE ENGINE SOON MIL.
^ Driveability problem
^ Engine will not start or stalls after start. UNDERSTANDING THE TABLE AND USING IT CORRECTLY WILL REDUCE DIAGNOSIS TIME AND PREVENT THE UNNECESSARY REPLACEMENT OF PARTS.