Diagnostic Procedure

The diagnostic procedures used in this section are designed to find and repair any 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 this may lead to a misdiagnosis or an 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 will assist 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 operation. Trying to diagnose a complaint that is normal will waste 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 procedures. Always begin here.
3. Are any DTCs displayed? If a DTC is identified by the diagnostics, the Powertrain OBD System Check will direct you to the appropriate table.
4. Is the customer's complaint related to a specific powertrain subsystem? If no related DTCs are set, the quickest way to locate the problem is to narrow 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 actually caused by other vehicle systems.