Testing Procedure

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

1. Record Customer Complaint
   
   Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
2. DLC3 Inspection
   
   Connect the OBD II scan tool or hand-held tester to Data Link Connector No. 3 (DLC3). See Fig 1. If the display indicates a communication fault in the tool, inspect the DLC3. See DATA LINK CONNECTOR NO. 3 INSPECTION  under SCAN TOOL PROBLEMS.
3. Retrieve DTCs & Freeze Frame Data
   
   Retrieve Diagnostic Trouble Codes (DTCs) and record any freeze frame data (if applicable). See RETRIEVING DIAGNOSTIC TROUBLE CODES  and FREEZE FRAME DATA  .
4. Clear DTCs & Freeze Frame Data
   
   Clear DTCs and freeze frame data. See CLEARING DIAGNOSTIC TROUBLE CODES .
5. Visual Inspection
   
   Inspect all electrical connectors and wiring for suspected circuit or component. Ensure all electrical connections are clean and tight.
6. Check Mode Diagnosis
   
   Set the check mode diagnosis. See CHECK MODE CODE RETRIEVAL  under RETRIEVING DIAGNOSTIC TROUBLE CODES.
7. Confirm Symptoms
   
   Perform road test. Determine if original symptoms are still present. If the engine does not start, perform steps  9 and  10 .
8. DTC Check
   
   Check the DTC. See SYSTEM OVERVIEW . If there is no malfunction code, go to next step. If there is a malfunction code, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS , then step  11.
9. Basic Inspection
   
   Perform basic inspection. See BASIC INSPECTION . If the results are OK, go to next step. If the results are not good, inspect the parts and then proceed to step  14.
10. Determine Symptom
    
    Determine problem symptoms. See SYMPTOM DIAGNOSIS under SYMPTOMS in TROUBLE SHOOTING - NO CODES article. If the problem is in the circuit, go to next step. If the problem is in the parts, inspect the parts and go to step  14.
11. Check ECM Power Source Circuit
    
    Check the ECM power source circuit. See SYSTEM & COMPONENT TESTING - V6 & V8 article.
12. Circuit Inspection
    
    Perform the appropriate circuit test. See DIAGNOSTIC TESTS . If the circuit is OK, go to step  14. If the circuit is not good, go to next step.
13. Intermittent Problem Check
    
    Check for intermittent problems. See INTERMITTENT PROBLEM CHECK .
14. Verification Procedure
    
    After repairs have been completed, clear all DTCs from ECM. See CLEARING DIAGNOSTIC TROUBLE CODES . Perform road test. Ensure no DTCs exist and all symptoms and/or complaints have been repaired.