GM Service Manual Online
For 1990-2009 cars only

Important Preliminary Inspections Before Beginning

Before using this section, perform the Diagnostic System Check - Engine Controls and verify all of the following conditions:

    • The powertrain control module (PCM) and the malfunction indicator lamp (MIL) are operating correctly. Refer to Malfunction Indicator Lamp (MIL) Inoperative .
    • Diagnostic trouble codes (DTCs) are not stored.
    • The scan tool data is within the normal operating range. Refer to Scan Tool Data List .
    • Verify the customer concern and locate the correct symptom table. Inspect the items indicated in that symptom table.
    • Several of the symptom procedures ask for a careful visual/physical inspection. This step is extremely important, and can lead to correcting a condition without further inspections and can save valuable time.
    • If the intermittent condition exists as a start and then stall, inspect for any DTCs related to the theft deterrent system. Refer to Diagnostic System Check - Theft Deterrent in Theft Deterrent.
    • Verify the proper installation of any of the following aftermarket accessories:
      • Lights
      • Cellular phone
      • Remote starter system
      • Aftermarket installed alarm
    • Use the following tables when diagnosing a symptom concern:
      •  Poor Fuel Fill Quality
      •  Hard Start
      •  Surges/Chuggles
      •  Lack of Power, Sluggishness, or Sponginess
      •  Detonation/Spark Knock
      •  Hesitation, Sag, Stumble
      •  Cuts Out, Misses
      •  Poor Fuel Economy
      •  Rough, Unstable, or Incorrect Idle and Stalling
      •  Dieseling, Run-On
      •  Backfire
    • If the condition cannot be isolated using the appropriate table, refer to Intermittent Conditions for further diagnosis.