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Data Link Connector Diagnosis

NOTE: For circuit reference, see WIRING DIAGRAMS article.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Turn ignition on, with engine off. Observe scan tool. If scan tool turns on, go to next step. If scan tool does not turn on, go to step  5.
  3. Attempt to establish communication with PCM. If scan tool displays any PCM data, system is okay. If scan tool does not display any PCM data, go to next step.
  4. Ensure all of the following scan tool selections are correct: model year, carline, engine option (VIN). Correct any error in selections. If scan tool displays engine data, system is okay. If scan tool does not display engine data, go to step  9.
  5. Using a DVOM, check voltage between ground and DLC terminal No. 16. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step  8.
  6. Using a test light connected to battery voltage, probe DLC terminals No. 4 and 5. If test light illuminated on both circuits, go to step  14. If test light did not illuminate, go to next step.
  7. Turn ignition off. Repair open in DLC ground circuits. After repairs, go to step  2.
  8. Turn ignition off. Repair open or short in battery positive voltage circuit to DLC. After repairs, go to step  2.
  9. Check voltage between ground and DLC terminal No. 7. If voltage reading is 11 volts or greater, go to next step. If voltage reading is not 11 volts or greater, go to step  12.
  10. Connect a test light between DLC terminal No. 7 and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  14.
  11. Turn ignition off. Repair short to battery voltage in serial data circuit. Check for scan tool damage that may have occurred with shorted circuit. After repairs, go to step  3.
  12. Turn ignition off. Check for open or short to ground in serial data circuit between PCM and DLC. Repair as necessary. After repairs, go to step  3. If circuit is okay, go to next step.
  13. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to step  3.
  14. Check connections to DLC and scan tool for bent or damaged terminals, or loose or pushed out terminals. Repair as necessary. After repairs, go to step  2. If connections and terminals are okay, go to next step.
  15. Scan tool is faulty. Repair or replace scan tool. After replacing scan tool, go to step  2.
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