Diagnostic Procedure

The diagnostic procedures used in this system are designed to find and repair powertrain related problems. The general approach is to find the appropriate diagnosis for a problem with the 5 basic steps described below.
1. Understand the customer's complaint. It is critical that the technician understand what the customer's complaint is. Failure to understand the complaint may lead to misdiagnosis or unnecessary diagnosis. Among other things, the technician must know whether the condition is present at all times, only under certain circumstances, or truly intermittent. This assists the technician in duplicating and diagnosing the problem. Another reason the technician must understand the customer's complaint is so the technician may determine whether the complaint requires service or is a normal vehicle condition. Trying to diagnose a complaint that is normal wastes time and may result in unnecessary service.
2. Are the diagnostics working properly? Use the Powertrain OBD System Check. This is the starting point for the diagnostic procedure. Always begin with the Powertrain OBD System Check.
3. Are DTCs displayed? If a DTC is identified by diagnostics, the Powertrain OBD System Check directs you to the appropriate table.
4. Is the customer's complaint related to a specific powertrain subsystem? If no related DTCs are set, the next quickest way to locate the problem is to narrow the the problem down to a specific powertrain subsystem. If a specific subsystem can be pinpointed as the cause, the problem is easier to diagnose.
5. Is the problem powertrain related? Some customer complaints may appear to be powertrain related but are actually caused by other vehicle systems.