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

  1. Connect scan tool to Data Link Connector (DLC). DLC is located on lower left side of instrument panel, near steering column. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST A: SCAN TOOL DOES NOT POWER UP  .
    2. NOTE: If using Tech 2 scan tool, obtain information using CLASS 2 MESSAGE MONITOR feature.
  2. Turn ignition switch to RUN position. Attempt to communicate with each module on class 2 serial data circuit. If scan tool communicates with any module on class 2 serial data circuit, go to next step. If scan tool does not communicate with any module on class 2 serial data circuit, go to step  6 .
  3. Using scan tool, select DISPLAY DTCs function for each module. Record DTCs, DTC status and which module set DTCs. If any DTCs within DTC U1000 to U1255 range are set, go to next step. If there are no DTCs within DTC U1000 and U1255 range set, go to step  5 .
  4. If DTC U1000 or U1255 are only DTCs displayed, go to DTC U1000 & U1255: CLASS 2 COMMUNICATION MALFUNCTION  under DIAGNOSTIC TESTS. If DTC U1000 or U1255 are not only DTCs displayed, go to DTC U1001-U1254: LOSS OF COMMUNICATIONS WITH XXX  under DIAGNOSTIC TESTS.
  5. Diagnose fault for non-communicating module(s). See DTC U1001-U1254: LOSS OF COMMUNICATIONS WITH XXX  under DIAGNOSTIC TESTS. After completion, perform appropriate diagnostic system check. See BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  6. Turn ignition switch to OFF position. Disconnect scan tool from DLC. Inspect DLC terminals No. 2 and 5 for poor connections and terminal tension. See Figure . Perform procedure while wiggling related wiring and connectors. This can often cause an intermittent malfunction to appear. If problem is not found, go to next step. If problem is found, repair as necessary. After repairs, perform appropriate diagnostic system check. See BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  7. Check for open circuit between DLC terminal No. 5 (Black/White wire) and ground. Ground point is located at lower right corner of passenger side pillar. If problem is not found, go to next step. If problem is found, repair as necessary. After repairs, perform appropriate diagnostic system check. See BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
    8. NOTE: Splice (w/UV6) in Purple wire is located in instrument panel harness from Instrument Panel Module (IPM) breakout. In-line harness connector (w/o UV6) in Purple wire is located at upper right side of instrument panel, under upper instrument panel trim pad.
  8. Check for open in Purple wire at DLC terminal No. 2. If problem is not found, go to next step. If problem is found, repair as necessary. After repairs, perform appropriate diagnostic system check. See BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  9. Disconnect Powertrain Control Module (PCM) Blue harness connector C1. PCM is located at front left side of engine compartment, inside air cleaner box. Disconnect Sensing and Diagnostic Module (SDM) harness connector. SDM is located under rear of center console. Connect scan tool to DLC. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  17 .
  10. Turn ignition switch to OFF position. Reconnect PCM harness connector C1. Disconnect Rear Integration Module (RIM) harness connectors. RIM is located behind left rear seat back cushion. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  12 .
  11. Turn ignition switch to OFF position. Check for short to ground in Purple wire between SDM harness connector terminal A5 and RIM harness connector terminal A12. Turn ignition switch to RUN position. Check for short to voltage in Purple wire between SDM harness connector terminal A5 and RIM harness connector terminal A12. If problem is not found, go to step  24 . If problem is not found, repair as necessary. After repairs, go to step  28 .
  12. Turn ignition switch to OFF position. Disconnect Remote Control Door Lock Receiver (RCDLR) 4-pin harness connector. RCDLR is located rear of passenger compartment behind rear seat back under rear shelf. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  14 .
  13. Turn ignition switch to OFF position. Check for short to ground in Purple wire between RCDLR harness connector terminal No. 2 and RIM harness connector terminal B12. Turn ignition switch to RUN position. Check for short to voltage in Purple wire between RCDLR harness connector terminal No. 2 and RIM harness connector terminal B12. See Fig 1 . If problem is not found, go to step  24 . If problem is found, repair as necessary. After repairs, go to step  28 .
  14. Turn ignition switch to OFF position. Disconnect Electronic Brake Control Module (EBCM) harness connector. EBCM is located in engine compartment, under air cleaner. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  16 .
  15. Turn ignition switch to OFF position. Check for short to ground in Purple wire between EBCM 29-pin harness connector C2 terminal No. 7 and RCDLR. See Fig 2 . Turn ignition switch to RUN position. Check for short to voltage in Purple wire between EBCM 29-pin harness connector C2 terminal No. 7 and RCDLR harness connector terminal No. 3. If problem is not found, go to step  24 . If problem is found, repair as necessary. After repairs, go to step  28 .
    Fig 1: Identifying Rear Integration Module Harness Connector C1 & C2 Terminals
    G00016049Courtesy of GENERAL MOTORS CORP.
    Fig 2: Identifying Electronic Brake Control Module Harness Connector C1 & C2 Terminals
    G00027210Courtesy of GENERAL MOTORS CORP.
  16. Turn ignition switch to OFF position. Check for short to ground in Purple wire between EBCM 29-pin harness connector C2 terminal No. 21 and PCM. See Fig 2 . Turn ignition switch to RUN position. Check for short to ground in Purple wire between EBCM 29-pin harness connector C2 terminal No. 21 and PCM. If problem is not found, go to step  24 . If problem is found, repair as necessary. After repairs, go to step  28 .
  17. Turn ignition switch to OFF position. Disconnect 40-pin in-line harness connector C200. In-line harness connector C200 is located at left lower corner of passenger compartment on underside of instrument panel. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  20 .
  18. Turn ignition switch to OFF position. Reconnect in-line harness connector C200. Disconnect Vehicle Theft Deterrent (VTD) module. VTD module is located behind instrument panel trim, on right side of radio. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  26 .
  19. Turn ignition switch to OFF position. Check for short to ground in Purple wire between VTD module harness connector terminals "D" and "E" and PCM. See Fig 3 . Turn ignition switch to RUN position. Check for short to voltage in Purple wire between PCM harness connector C1 terminal No. 59 and VTD module harness connector terminals "D" and "E". If problem not found, go to step  24 . If problem is found, repair as necessary. After repairs, go to step  28 .
  20. Turn ignition switch to OFF position. Disconnect radio 32-pin harness connector. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  22 .
  21. Turn ignition switch to OFF position. Check for short to ground in Purple wire between radio harness connector terminal A2 and DLC. See Fig 4 . Turn ignition switch to RUN position. Check for short to voltage in Purple wire between radio harness connector terminal A2 and DLC terminal No. 2. If problem is not found, go to step  24 . If problem is found, repair as necessary. After repairs, go to step  28 .
    Fig 3: Identifying Vehicle Theft Deterrent Module Harness Connector Terminals
    G00060849Courtesy of GENERAL MOTORS CORP.
    Fig 4: Identifying Radio Harness Connector Terminals
    G00060853Courtesy of GENERAL MOTORS CORP.
  22. Turn ignition switch to OFF position. Disconnect Dash Integration Module (DIM) 24-pin Brown harness connector C2. DIM is located behind instrument panel, under right sound insulator. Check for short to ground in Purple wire between DIM harness connector C2 terminal A12 and radio. See Figure . Check for short to ground in Purple wire between DIM harness connector C2 terminal A11 and SDM. Turn ignition switch to RUN position. Check for short to voltage in Purple wire between DIM harness connector C2 terminal A12 and radio. Check for short to voltage in Purple wire between DIM harness connector C2 terminal A11 and SDM. If problem is not found, go to next step. If problem is found, repair as necessary. After repairs, go to step  28 .
    23. NOTE: Splice (w/UV6) in Purple wire is located in instrument panel harness from Instrument Panel Module (IPM) breakout. In-line harness connector (w/o UV6) in Purple wire is located at upper right side of instrument panel, under upper instrument panel trim pad.
  23. Turn ignition switch to OFF position. Check for short to ground in Purple wire between DLC terminal No. 2 and splice (w/UV6), or in-line harness connector (w/o UV6). Turn ignition switch to RUN position. Check for short to voltage in Purple wire between DLC terminal No. 2 and splice or in-line harness connector. If problem is not found, go to next step. If problem is found, repair as necessary. After repairs, go to step  28 .
  24. Connect all disconnected modules except for those in suspect area of class 2 serial data circuit. Connect any other disconnected connectors. Connect one of the disconnected modules in suspect area of class 2 serial data circuit. Connect scan tool to DLC. Turn ignition switch to RUN position. Attempt to communicate with any module still connected to class 2 serial data circuit. If scan tool communicates with any module on serial data circuit, go to next step. If scan tool does not communicate with any module on serial data circuit, go to step  26 .
  25. Continue connecting disconnected modules and attempting to communicate after each connection until communications cannot be established or all modules are connected. If problem is found, repair as necessary. After repairs, go to step  27 . If problem is not found, go to step  28 .
  26. Repair Purple wire between VTD module terminal(s) "D" and/or "E" and in-line harness connector C200. After repairs, go to step  28 .
  27. Replace most recently connected module. See REMOVAL & INSTALLATION  . After replacement, go to next step.
    28. NOTE: Scan tool may require a power up reset before communication will occur due to a short on class 2 serial data circuit. Turn off or disconnect scan tool before displaying DTCs.
    NOTE: If using Tech 2 scan tool, use CLASS 2 DTC CHECK feature in order to determine which modules have DTCs set.
  28. Connect all disconnected modules except for those in suspect area of class 2 serial data circuit. Connect any other disconnected connectors. Connect one of the disconnected modules in suspect area of class 2 serial data circuit. Connect scan tool to DLC. Turn ignition switch to RUN position. Wait for 10 seconds. Using scan tool, select DISPLAY DTCs function for each module. Record all displayed DTCs and DTC status. If no DTCs are recorded which begin with "U" and with current status, go to next step. If any DTCs are recorded which begin with "U" and with current status, go to step  30 .
  29. If any DTCs were recorded which do not begin with "U", go to next step. If no DTCs were recorded which do not begin with "U", go to step  32 .
  30. Perform appropriate test in accordance with DTC retrieved for particular module or malfunction. PCM may have DTC(s) P1602 to P1615, or P1626 set. If only P1600 DTC(s) in range specified along with history U1XXX DTC(s) are set and vehicle will start and run, action is complete. After completion, go to next step.
  31. If all DTCs have not been diagnosed, go to step  30 . If all DTCs have been diagnosed, go to next step.
  32. Using scan tool, clear DTCs. System is okay.
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