Important Preliminary Checks Before Starting

Perform the Diagnostic System Check - Engine Controls before using the symptom tables. Verify that all of the following conditions are true:

• The engine control module (ECM) and the malfunction indicator lamp (MIL) are operating correctly.
• There are no diagnostic trouble codes (DTCs) 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 listed below. Inspect items indicated under that symptom.
• Several of the symptom procedures direct the technician to perform a visual/physical inspection. This important step can lead the technician to the cause of the problem without further checks and can save valuable time.
• Verify the correct installation and operation of electronic options, such as lights and cellular phones.