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Test B: Scan Tool Does Not Communicate With Class 2 Device: Notes

  1. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel, on hood release bracket. If scan tool powers up, go to next step. If scan tool does not power up, perform TEST A: SCAN TOOL DOES NOT POWER UP  .
  2. Turn ignition switch to RUN position. Attempt to communicate with each module on class 2 serial data line. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  7 .
  3. Using scan tool, select DISPLAY DTCs function for each module. If DTCs between U1000 and U1255 are retrieved, go to next step. If DTCs between U1000 and U1255 are not retrieved, see DIAGNOSTIC AIDS  .
  4. If DTC U1300, U1301 or U1305 are retrieved, go to next step. If DTCs U1300, U1301 or U1305 are not retrieved, go to step  6 .
  5. Turn ignition switch to RUN position. Using a DVOM, capture intermittent conditions using MIN/MAX functions. Inspect Purple wire for an intermittent short to ground or short to voltage between ground and DLC terminal No. 2. If an intermittent short to ground or short to voltage is not found, go to next step. If an intermittent short to ground or short to voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  6. If U1000 or U1255 are only DTCs displayed, perform DTC U1000 & U1255: CLASS 2 COMMUNICATION MALFUNCTION  under DIAGNOSTIC TESTS. If U1000 or U1255 are not only DTCs displayed, perform DTC U1001-U1254: LOSS OF XXX COMMUNICATIONS  under DIAGNOSTIC TESTS.
  7. Diagnose malfunction by performing DTC U1001-U1254: LOSS OF XXX COMMUNICATIONS  under DIAGNOSTIC TESTS. After test is completed, perform appropriate diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  table under SELF-DIAGNOSTIC SYSTEM.
  8. Turn ignition switch to OFF position. Disconnect scan tool from DLC. Inspect DLC for poor connections. If poor connections are not found, go to next step. If poor connections are found, repair DLC as necessary. After repair, perform appropriate diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  table under SELF-DIAGNOSTIC SYSTEM.
  9. Inspect Black wire for an open or high resistance between ground and DLC terminal No. 4. See Figure . If an open or high resistance is not found, go to next step. If an open or high resistance is found, repair Black wire as necessary between DLC and ground. Ground point is located behind left kick panel. After repair, perform appropriate diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  table under SELF-DIAGNOSTIC SYSTEM.
  10. Inspect Purple wire for an open or short to ground or voltage between DLC terminal No. 2 and Electronic Brake Control Module (EBCM) harness connector C2 terminal No. 26 and Powertrain Control Module (PCM) harness connector C1 terminal No. 18. See Figure , Fig 1 and Fig 2 . If an open or short to ground or voltage is not found, go to next step. If an open or short to ground or voltage is found, repair Purple wire as necessary. After repair, perform appropriate diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  table under SELF-DIAGNOSTIC SYSTEM.
    Fig 1: Identifying Electronic Brake Control Module Harness Connector Terminals
    G00020241Courtesy of GENERAL MOTORS CORP.
    Fig 2: Identifying Powertrain Control Module Harness Connector C1 & C2 Terminals
    G00012127Courtesy of GENERAL MOTORS CORP.
  11. Disconnect Powertrain Control Module (PCM) 80-pin harness connector C1. PCM is located on left front corner of engine compartment, below air cleaner housing. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  13 .
  12. Replace PCM, then go to step  54 .
  13. Turn ignition switch to OFF position. disconnect Electronic Brake Control Module (EBCM) 25-pin harness connector. EBCM is located on left front corner of engine compartment, on brake pressure modulator valve. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module still connected with DLC, go to next step. If scan tool does not communicate with any module still connected with DLC, go to step  16 .
  14. Inspect Purple wire for a short to ground or voltage between EBCM harness connector terminal No. 10 and PCM harness connector C1 terminal No. 18. See Fig 1 and Fig 2 . If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  15. Replace EBCM, then go to step  54 .
  16. Turn ignition switch to OFF position. Disconnect radio harness connector. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any modules till connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  18 .
  17. Replace radio, then go to step  54 .
  18. Turn ignition switch to OFF position. Disconnect Instrument Panel Cluster (IPC) 24-pin harness connector C2. IPC is located behind instrument cluster. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  20 .
  19. Replace IPC, then go to step  54 .
  20. Turn ignition switch to OFF position. Disconnect Heating Ventilation Air Conditioning (HVAC) control module 16-pin harness connector. HVAC is located behind center of instrument pane, below radio. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  23 .
  21. Inspect Purple wire for a short to ground or voltage between IPC harness connector C3 terminal D1 and HVAC control module harness connector terminal A8. If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  22. Replace HVAC control module, then go to step  54 .
  23. If vehicle is equipped with memory and personalization system, go to next step. If vehicle is not equipped with memory and personalization system, go to step  27 .
  24. Turn ignition switch to OFF position. Disconnect Memory Mirror Module (MMM) 32-pin harness connector. MMM is located below left side of instrument panel, above brake pedal. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  27 .
  25. Inspect Purple wire for a short to ground or voltage between HVAC control module harness connector terminal D2 and MMM harness connector terminal F16. See Fig 3 and Fig 4 . If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
    Fig 3: Identifying Memory Mirror Module & Radio Harness Connector Terminals
    G00020245Courtesy of GENERAL MOTORS CORP.
    Fig 4: Identifying Heating Ventilation Air Conditioning Control Module Harness Connector Terminals
    G00016868Courtesy of GENERAL MOTORS CORP.
  26. Replace MMM, then go to step  54 .
  27. Turn ignition switch to OFF position. Disconnect HVAC control module 16-pin harness connector. HVAC control module is located behind center of instrument panel, below radio. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  30 .
  28. Inspect Purple wire for a short to ground or voltage between HVAC control module harness connector terminal D2 and MMM harness connector terminal F16. See Fig 3 and Fig 4 . If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  29. Replace HVAC control module, then go to step  54 .
  30. If vehicle is equipped with a cellular phone, go to next step. If vehicle is not equipped with a cellular phone, go to step  33 .
  31. Turn ignition switch to OFF position. Disconnect Vehicle Interface Unit (VIU) 32-pin harness connector. VIU is located mounted to rear seat back panel. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  33 .
  32. Replace VIU, then go to step  54 .
  33. If vehicle is equipped with memory and personalization system, go to next step. If vehicle is not equipped with memory and personalization system, go to step  37 .
  34. Turn ignition switch to OFF position. Disconnect Memory Seat Module (MSM) 26-pin harness connector. MSM is located below driver's seat. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  37 .
  35. Inspect Purple wire for a short to ground or voltage between MSM harness connector C1 terminal No. 26 and radio harness connector terminal E6. See Fig 5 . If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
    Fig 5: Identifying Memory Seat Module Harness Connector C1 Terminals
    G98F01728Courtesy of GENERAL MOTORS CORP.
  36. Replace MSM, then go to step  54 .
  37. Turn ignition switch to OFF position. Disconnect Sensing & Diagnostic Module (SDM) 24-pin harness connector. SDM is located on left side of passenger compartment, below driver's seat. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  40 .
  38. Inspect Purple wire for a short to ground or voltage between SDM harness connector terminal No. 17 and radio harness connector terminal E6. If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  39. Replace SDM, then go to step  54 .
  40. If vehicle is equipped with variable road sensing suspension, go to next step. If vehicle is not equipped with variable road sensing suspension, go to step  43 .
  41. Turn ignition switch to OFF position. Disconnect Continuously Variable Road Sensing Suspension (CVRSS) module 32-pin harness connector. CVRSS module is located behind rear seat in passenger compartment. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  43 .
  42. Replace CVRSS module, then go to step  54 .
  43. If vehicle is equipped with Bose(R) speaker system, go to next step. If vehicle is not equipped with Bose(R) speaker system, go to step  48 .
  44. Turn ignition switch to OFF position. Disconnect Radio Interface Module (RIM) 32-pin harness connector. RIM is located behind rear seat in passenger compartment. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  48 .
  45. If vehicle is equipped with variable road sensing suspension, go to next step. If vehicle is not equipped with variable road sensing suspension, go to step  48 .
  46. Inspect Purple wire for a short to ground or voltage between CVRSS harness connector C1 terminal D5 and RIM harness connector C1 terminal B2. If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  47. Replace RIM, then go to step  54 .
  48. Turn ignition switch to OFF position. Disconnect Remote Control Door Lock Receiver (RCDLR) 4-pin harness connector. RCDLR is located behind rear seat in passenger compartment. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with any module still connected with DLC. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  52 .
  49. If vehicle is equipped with variable road sensing suspension or Bose(R) speaker system, go to next step. If vehicle is not equipped with variable road sensing suspension or Bose(R) speaker system, go to step  51 .
  50. Inspect Purple wire for a short to ground or voltage between RCDLR module harness connector terminal No. 2 and RIM harness connector terminal B3. If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  51. Replace RCDLR module, then go to step  54 .
  52. Inspect Purple wire for a short to ground or voltage between RCDLR harness connector terminal No. 2 and Body Control Module (BCM) harness connector C1 terminal A2, Powertrain Control Module (PCM) harness connector C1 terminal No. 59, radio harness connector terminal F6, VIU harness connector terminal A2 and HVAC control module harness connector C2 terminal D4. Inspect Purple wire for a short to ground or voltage between EBCM harness connector C2 terminal No. 26 and BCM harness connector C1 terminal A1. If a short to ground or voltage is not found, go to next step. If a short to ground or voltage is found, repair Purple wire as necessary. After repair, go to step  54 .
  53. Replace BCM, then go to next step.
    54. NOTE: Scan tool may require a power up reset before communication will occur. Turn off or disconnect scan tool before attempting to display DTCs.
  54. Connect all module harness connectors, if still disconnected. Connect scan tool to DLC. DLC is located below left side of instrument panel, on hood release bracket. Turn ignition switch to RUN position, and wait 10 seconds. Using scan tool, select DISPLAY DTCS function for each module. If scan tool does not display any DTCs which begin with "U" and with a current status, go to next step. If scan tool displays any DTCs which begin with "U" and with a current status, go to step  56 .
  55. If scan tool displays any DTCs which do not being with "U", go to next step. If scan tool does not display any DTCs which do not begin with "U", go to step  58 .
  56. Diagnose DTCs for module they are set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If DTC P1600 is set in PCM and vehicle will start and run, repair is complete. After repairs, go to next step.
  57. If all DTCs have been diagnosed, go to next step. If any DTC has not been diagnosed, go to step  56 .
  58. Using scan tool, clear DTCs. System should be operating correctly at this time.
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