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DLC Diagnosis Or No Scan Tool Data

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Check all PCM power and ground connections and circuits. Repair as necessary. After repairs, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If connections and circuits are okay, go to next step.
  3. Ensure battery is fully charged. Using DVOM, check voltage between DLC battery feed circuit and DLC ground circuits. See ENGINE PERFORMANCE - WIRING DIAGRAMS article. Voltage reading for both circuits should be 10 volts. If voltage readings are the same or higher for both circuits, go to step 7). If voltage readings are not the same or higher for both circuits, go to next step.
  4. Using DVOM, check voltage between ground and DLC battery feed circuit. See ENGINE PERFORMANCE - WIRING DIAGRAMS article. Voltage reading should be about 10 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 6).
  5. Repair open in DLC ground circuit that had low or no voltage. After repairs, go to step 7).
  6. Repair open or short to ground in DLC battery feed circuit. Replace blown fuse as necessary. After repairs, go to next step.
  7. Turn ignition on. If scan tool displays PCM data, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If scan tool does not display PCM data, go to next step.
  8. Install scan tool on another vehicle and check for proper operation. If scan tool operates properly, go to next step. If scan tool does not operate properly, go to step 13).
  9. Reinstall scan tool on original vehicle and enter on-board diagnostics. If on-board diagnostics is entered, go to next step. If on-board diagnostics cannot be entered, diagnose vehicle computer system.
  10. Using on-board diagnostics display, check all control modules for Diagnostic Trouble Codes (DTCs). If DTCs are present, diagnose DTCs. If DTCs are not present, go to next step.
  11. Check for open in class II serial data circuit between DLC and PCM. Repair as necessary. After repairs, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If circuit is okay, go to next step.
  12. Check DLC terminal connection. Repair as necessary. Exit on-board diagnostics. Reconnect scan tool. If scan tool displays PCM data, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If scan tool does not display PCM data, go to step 14).
  13. Replace faulty scan tool. After replacing scan tool, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
  14. Replace PCM. Perform PCM relearn procedures. After replacing PCM, perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
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