- Symptoms - Engine Controls

SYMPTOMS - COMPUTERS AND CONTROL SYSTEMS

IMPORTANT PRELIMINARY INSPECTIONS BEFORE BEGINNING
Perform Diagnostic Trouble Code (DTC) List - Vehicle before using the symptom tables, and verify that all of the following are true:
- The control module and malfunction indicator lamp (MIL) are operating correctly.
- There are no DTCs stored.
- The scan tool data is within the normal operating range, refer to Scan Tool Data List. Scan Tool Data List
- Verify the customer concern and locate the correct symptom. Inspect the items indicated under that symptom.
- Several of the symptom procedures ask for a careful visual and physical inspection. This step is extremely important. The visual and physical inspection can lead to correcting a problem without further inspections, and can save valuable time.
- Inspect for improper installation of electrical components if an intermittent condition exists. Inspect for aftermarket theft deterrent devices, lights, and cellular phones. If you can not locate an intermittent condition, a cellular phone communication signal may cause the condition.
- If the intermittent condition exists as a start and then stall, test for DTCs relating to the vehicle theft deterrent system. Diagnostic Trouble Code Descriptions

Use the following tables when diagnosing a symptom complaint:
- 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