GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2005 🢒 L300/LW300 🢒 General Information 🢒 Vibration Diagnosis and Correction 🢒 Symptoms - Engine Controls

Important Preliminary Inspections Before Beginning

Before using this section, perform the Diagnostic System Check - Vehicle in Vehicle DTC Information and verify all of the following conditions:

    • The engine control module (ECM) 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.
    • Verify the proper installation of any of the following aftermarket accessories:
       - Lights
       - Cellular phone
       - Remote starter system
       - Aftermarket installed alarm
  1. Use the following tables when diagnosing a symptom concern:
    2. •  Hard Start
    •  Surges/Chuggles
    •  Lack of Power, Sluggishness, or Sponginess
    •  Detonation/Spark Knock
    •  Hesitation, Sag, Stumble
    •  Cuts Out, Misses
    •  Poor Fuel Economy
    •  Poor Fuel Fill Quality
    •  Rough, Unstable, or Incorrect Idle and Stalling
    •  Dieseling, Run-On
    •  Backfire
  2. If the condition cannot be isolated using the appropriate table, refer to Intermittent Conditions for further diagnosis.