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Data Link Connector Diagnosis Or No Scan Tool Data

NOTE: Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC SYSTEM CHECK .
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Connect scan tool to a known-good vehicle. If scan tool displays VCM data, go to step  4. If scan tool does not display VCM data, go to next step.
  3. Repair scan tool or scan tool cables.
  4. Reconnect scan tool to original vehicle. If scan tool powers up, go to next step. If scan tool does not power up, go to step  9.
  5. Using scan tool, select correct vehicle application. If vehicle information is correct, go to next step. If vehicle information is not correct, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK .
  6. Turn ignition on. Using scan tool, monitor class II serial data. If any modules on serial data circuit are communicating, go to step  13. If no modules communicate, go to next step.
  7. Turn ignition off. Disconnect components sharing serial data circuit, leaving VCM connected. Turn ignition on, with engine off. If scan tool displays VCM data, diagnose class II serial data circuit. See WIRING DIAGRAMS article. If scan tool does not display VCM data, go to next step.
  8. Turn ignition off. Disconnect VCM harness connector C4. See WIRING DIAGRAMS article. Using a test light connected to battery positive, probe class II serial data circuit at DLC (terminal No. 2). If test light illuminates, go to step  20. If test light does not illuminate, go to step  13.
  9. Using a test light connected to ground, probe battery positive feed circuit at DLC (terminal No. 16). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  12.
  10. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 4). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  16.
  11. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 5). See WIRING DIAGRAMS article. If test light illuminates, go to step  18. If test light does not illuminate, go to step  16.
  12. Inspect fuse associated with battery feed circuit. If fuse is open, go to step  14. If fuse is okay, go to step  15.
  13. Check for open or poor connection in class II serial data circuit. If a problem is found, go to step  17. If circuit is okay, go to step  19.
  14. Check for short to ground in battery feed circuit. Repair as necessary and replace fuse. After repairs, go to step  23.
  15. Repair open in battery feed circuit. After repairs, go to step  23.
  16. Repair open in DLC ground circuit. After repairs, go to step  23.
  17. Repair open or poor connection in class II serial data circuit. After repairs, go to step  23.
  18. Check for poor connections at DLC. If a problem is found, go to step  21. If connections are okay, see appropriate TROUBLE SHOOTING - NO CODES article.
  19. Check class II serial data circuit for poor connections at VCM and DLC. If a problem is found, go to step  21. If circuit connections are okay, go to step  22.
  20. Repair short to ground in class II serial data circuit. After repairs, go to step  23.
  21. Repair circuit as necessary. After repairs, go to step  23.
  22. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  23. Using scan tool, check for DTCs. If any additional DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS . If no DTCs are present, system is okay.
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