Important Preliminary Inspections
Before Starting
Before using this section, perform the 
Diagnostic System Check - Vehicle in Vehicle
DTC Information and ensure that the following items are OK:
|     •  | The engine control module (ECM), malfunction indicator lamp (MIL), and
 check engine are operating correctly. | 
 
|     •  | There are no DTCs stored. | 
 
Verify the customer complaint and locate the correct symptom in the table of
contents. Inspect the items indicated under that symptom.
Visual/Physical Inspection
Several of the symptom procedures call for a careful visual/physical check.
 The importance of this step cannot be stressed strongly enough. This step can lead
 to correcting a condition without further inspections and can save valuable time.
This inspection should include:
|     •  | ECM grounds for the following conditions: | 
 
|     •  | Vacuum hoses for the following conditions: | 
 
|     •  | Air leaks at the following components: | 
 
|        -  | Intake manifold sealing surfaces | 
 
|     •  | Wiring for the following conditions: | 
 
|     •  | Use the following tables when diagnosing a symptom complaint: |