Testing Procedure

To ensure correct diagnosis and repair, testing should be done in the following sequence:

• Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
• Retrieve Diagnostic Trouble Codes Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See RETRIEVING DIAGNOSTIC TROUBLE CODES.
• Clear Trouble Codes Clear codes using scan tool. See CLEARING DIAGNOSTIC TROUBLE CODES.
• Perform Visual Inspection Inspect all connectors of suspect circuit or component. Ensure all connections are clean and tight.
• Confirm Symptoms & Trouble Codes Perform road test. Determine if original symptoms are still present. Retrieve codes.
• Diagnose & Repair Diagnostic Trouble Codes Perform diagnosis and repair procedures as needed. If no codes are present, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
• Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See CLEARING DIAGNOSTIC TROUBLE CODES. Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.