Diagnostic Procedure

Use the diagnostic procedures in order to resolve powertrain related problems. Find the appropriate diagnosis for a problem by using the five basic steps below.
1. Understand the customer's concerns. The technician must understand what the customer's concern is. Failure to understand the customer concern may lead to misdiagnosis or to unnecessary diagnosis. The technician must know if the condition is present at all times, under certain circumstances, or is intermittent. This knowledge will assist the technician in duplicating the problem and in diagnosing the problem. Understanding the customer's concern enables the technician to determine if the condition requires service or is a characteristic of normal vehicle operation. Trying to diagnose a customer concern that is a normal characteristic of vehicle operation may result in unnecessary service.
2. Are the diagnostics that are built into the PCM working correctly? Use the Powertrain OBD System Check. Always begin the diagnostic procedure at this starting point.
3. Are any DTCs set? If the diagnostics identity any DTCs, the Powertrain OBD System Check will direct you to the appropriate table.
4. Is the customer's concern related to a specific powertrain subsystem? If related DTCs are not set, attempt to link the problem to a specific powertrain subsystem. If a specific subsystem car be identified as the cause of the problem, the diagnosis will be quicker and easier.
5. Is the customer's concern powertrain related? Some customer concerns that are caused by other vehicle systems may appear to be powertrain related.