Powertrain System Diagnosis

After the Visual Inspection  is complete, the Powertrain System Check, CHART 1 , should be performed. The Powertrain System Check will provide direction for diagnosis of:

• PCM inoperative or damaged (No PCM data or "SERVICE ENGINE SOON" MIL inoperative).
• PCM trouble codes current or history.
• Fuel System Rich or Lean.
• Customer Complaint Driveability Symptoms.

The Powertrain System Check is designed as a "Master" chart for driveability and emissions system diagnosis. The System Check should always be used as the starting point for all Powertrain diagnosis. The Powertrain 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 stall after start.

Understanding the chart and using it correctly will reduce diagnosis time and prevent the unnecessary replacement of parts.