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Test C: Scan Tool Does Not Communicate With Class 2 Device

  1. Install scan tool. If scan tool powers up, go to next step. If scan tool does not power up, diagnose data link connector circuit. See DATA LINK CONNECTOR article in WIRING DIAGRAMS.
  2. Turn ignition on, with engine off. Using scan tool, attempt to communicate with each module on the class 2 circuit. If scan tool communicates with any module on the class 2 circuit, go to next step. If scan tool does not communicate with any module on the class 2 circuit, go to step  5.
  3. Using scan tool, select display DTCs function for each module. Record all of displayed DTCs, DTC status and module which set the DTC. If any recorded DTCs are in the range of U1000 to U1255, go to next step. If no DTCs are recorded, problem is intermittent.
  4. If DTC U1000 or U1255, or DTC U1001-U1254 are displayed, diagnose affected DTC(s). Go to appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  5. Turn ignition off. Remove scan tool from DLC. Check DLC terminals No. 2 and 5 for poor connections. Repair as necessary. After repairs, go to next step.
  6. Check for open in DLC signal ground circuit. Repair as necessary. After repairs, go to next step.
  7. Leave SP261 splice pack connected. SP261 splice pack is located about 8" from relay block near DLC. Check continuity from SP261 pin "A" to every other pin on splice pack. Remove comb from SP261 splice pack. Check for poor connections at splice pack. Repair as necessary. After repairs, go to next step.
  8. Check for open or short in DLC class 2 circuit. Repair as necessary. After repairs, go to next step.
  9. Connect a jumper wire between DLC class 2 circuit and BCM class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with BCM. If scan tool communicates with BCM, go to step  11. If scan tool does not communicate with BCM, go to next step.
  10. Turn ignition off. Disconnect BCM harness connector C1. Check BCM class 2 circuit for short to battery negative or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  11. Leave jumper wires connected to BCM and DLC class 2 circuits. Connect another jumper wire between DLC class 2 circuit and VCM class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with VCM. If scan tool communicates with VCM, go to step  13. If scan tool cannot communicate with VCM, go to next step.
  12. Turn ignition off. Remove VCM harness connector C1. Check VCM class 2 circuit for short to battery negative voltage or a short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  13. Remove jumper wire from VCM class 2 circuit and connect jumper wire to end of Traction Control System (TCS) control module class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with TCS control module. If scan tool communicates with TCS control module, go to step  15. If scan tool does not communicate with TCS control module, go to next step.
  14. Turn ignition off. Disconnect Automatic Transfer Case (ATC) control module harness connector C1. Check TCS control module class 2 circuit for short to battery negative voltage or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  15. Remove jumper wire from TCS control module class 2 circuit and connect jumper wire to end of EBCM class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with EBCM. If scan tool communicates with EBCM, go to step  17. If scan tool does not communicate with EBCM, go to next step.
  16. Turn ignition off. Remove connector that contains class 2 circuit at EBCM. Check EBCM class 2 circuit for short to battery negative voltage or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  17. Remove jumper wire from EBCM class 2 circuit and connect jumper wire to end of SDM class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with SDM. If scan tool communicates with SDM, go to step  19. If scan tool does not communicate with SDM, go to next step.
  18. Turn ignition off. Disconnect Sensing and Diagnostic Module (SDM) harness connector. Check SDM class 2 circuit for short to battery negative voltage or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  19. Remove jumper wire from SDM class 2 circuit and connect jumper wire to end of IPC class 2 circuit. Turn ignition on, with engine off. Using scan tool, attempt to communicate with IPC. If scan tool communicates with IPC, go to step  21. If scan tool does not communicate with IPC, go to next step.
  20. Turn ignition off. Disconnect IPC harness connector. Check IPC class 2 circuit for short to battery negative voltage or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  25.
  21. Remove jumper wire from IPC class 2 circuit and connect jumper wire to Driver Information Center (DIC) class 2 circuit. Using scan tool, attempt to communicate with DIC. If scan tool communicates with DIC, go to step  23. If scan tool does not communicate with DIC, go to next step.
  22. Turn ignition off. Disconnect DIC connector that contains DIC class 2 circuit. Check DIC class 2 circuit for short to battery negative voltage or short to battery positive voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to next step.
  23. Remove jumper wire from DIC class 2 circuit. Connect jumper wire to each end of redundant BCM/VCM class 2 circuit. Attempt to view all data on overhead console. If overhead console displays all of necessary data, go to step  25. If overhead console does not display all of necessary data, go to next step.
  24. Turn ignition off. Disconnect BCM harness connector C1. Check the redundant BCM/VCM class 2 circuit for short to battery voltage or short to battery negative voltage. Turn ignition on, with engine off when testing for short to voltage. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to next step.
  25. Check for poor connections at class 2 circuit of module that is not communicating. Repair as necessary. After repairs, go to step  27. If connections are okay, go to next step.
  26. Replace module which is not communicating. After replacing affected module(s), go to next step.
  27. Reconnect all modules and connectors. Connect scan tool. Turn ignition on, with engine off. Wait for 10 seconds. Scan tool may require a power up reset before communication will occur due to short on the class 2 circuit. Turn off or disconnect scan tool prior to performing this test. Using scan tool, select display DTCs function for each module. Record all of displayed DTCs and DTC status. Diagnose affected DTCs. If no DTCs are displayed, clear DTCs.
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