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Home >> Infiniti >> 2004 >> QX56 AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 213 (Body Control Modules) >> System Tests >> Test B: Scan Tool Does Not Communicate With Class 2 Device >> Test Procedure
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Test Procedure

WARNING: This page is about a different car, the 2002 Pontiac Grand Am and 2002 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to Data Link Connector (DLC). DLC is located under driver side of instrument panel. 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. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with each module on Class 2 serial data line. If scan tool communicates with one or more modules, 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 and retrieve DTCs for each module. Record DTCs, DTC status and which module stored DTC(s). If any DTCs between DTC U1000 and U1255 are stored, go to next step. If no DTCs are stored, disconnect all non-communicating harness connectors. Inspect harness connectors for loose, corroded or pushed-out pins. Reconnect all harness connectors, ensuring that connectors are seated properly. Operate system, and verify that concern still exists. If concern does not exist, fault may be intermittent.
  4. Review recorded scan tool data. If DTCs U1300, U1301 or U1305 are stored, go to next step. If DTCs U1300, U1301 or U1305 are not stored, go to step  6 .
  5. Turn ignition switch to RUN position. Use DVOM MIN/MAX function to capture intermittent conditions. Check Class 2 data line for intermittent short to ground or short to voltage (Purple wire). See CONNECTOR IDENTIFICATION  and WIRING DIAGRAMS  . If no problem is found, go to  10 . Repair as necessary and go to step  24 .
  6. Review scan tool data. If DTCs U1000 or U1255 are only DTCs stored, go to DTC U1000 OR U1255: CLASS 2 COMMUNICATION MALFUNCTION  under DIAGNOSTIC TESTS. If DTCs U1000 or U1255 are not only DTCs stored, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  7. Turn ignition switch to OFF position. Disconnect scan tool. Inspect DLC terminals No. 2 and 5 for poor or loose connections and terminal tension. See Figure . If no problem is found, go to next step. If problem is found, repair as necessary and go to step  24 .
  8. Measure resistance between ground and DLC harness connector terminal No. 5 (Black/White wire). See Figure . Ground point is located under instrument panel on driver side of dash. If continuity exists, go to next step. If continuity does not exists, repair as necessary and go to step  24 .
  9. Disconnect all driver side Instrument Panel (IP) junction block harness connectors. Driver side IP junction block is located at driver end of instrument panel. See Figure . Inspect driver side IP junction block harness connector/terminal C1/A3, C1/D2, C1/E3, C2/A8 and C3/A5 for poor or loose connections and terminal tension. Disconnect Pink BCM 24-pin harness connector C3. BCM is located under passenger side of instrument panel. See Figure . Check for an open between DLC terminal No. 2 and driver side IP junction block harness connector C1 terminal D2. Check for a short to voltage or ground in all Class 2 wiring. See CONNECTOR IDENTIFICATION  and WIRING DIAGRAMS  . If no problem is found, go to next step. If problem is found, repair as necessary and go to step  24 .
  10. Turn ignition switch to OFF position position. Reconnect all connectors except Pink BCM 24-pin harness connector C3. Connect scan tool to DLC and turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool can communicate with modules on Class 2 data line, go to step  23 .
  11. Turn ignition switch to OFF position. Disconnect Instrument Panel Cluster (IPC) Gray 24-pin harness connector. Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool communicates with other modules on Class 2 data line, go to step  23 .
  12. Turn ignition switch to OFF position. Disconnect Inflatable Restraint Sensing and Diagnostic Module (SDM) 18-pin harness connector. SDM is located under passenger front seat. See Figure . Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules, go to next step. If scan tool communicates with other modules, go to step  23 .
  13. Turn ignition switch to OFF position. Disconnect radio Gray 24-pin harness connector. Harness connector is located on back of radio. Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool communicates with other modules on Class 2 data line, go to step  23 .
  14. If vehicle is not equipped with digital radio receiver go to next step. Turn ignition switch to OFF position. Disconnect digital radio receiver (if equipped) Gray 24-pin harness connector. Harness connector is located on back of radio. Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool communicates with other modules on Class 2 data line, go to step  23 .
  15. Turn ignition switch to OFF position. Disconnect Electronic Brake Control Module (EBCM) 37-pin harness connector. EBCM is located inside driver front fender. Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool communicates with other modules on Class 2 data line, go to step  23 .
  16. Turn ignition switch to OFF position. Connect SDM harness connector. Disconnect Powertrain Control Module (PCM) 80-pin harness connector C1. PCM is located under instrument panel, next to steering column. See Figure . Connect scan tool to Data Link Connector (DLC). Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules on Class 2 data line, go to next step. If scan tool communicates with other modules on Class 2 data line, go to step  23 .
  17. If vehicle is equipped with Remote Control Door Lock Receiver (RCDLR) module, go to next step. If vehicle is not equipped with RCDLR module, go to step  19 .
  18. Ensure SDM harness connector is still connected. Turn ignition switch to OFF position. Disconnect RCDLR module 4-pin harness connector. RCDLR is located on rear package shelf between package shelf and trim panel. See Figure . Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules, go to next step. If scan tool communicates with other modules, go to step  23 .
  19. If vehicle is an export model, it may be equipped with a Vehicle Theft Deterrent (VTD) module. If vehicle is equipped with VTD module, go to next step. If vehicle is not equipped with VTD module, go to step  21 .
  20. Turn ignition switch to OFF position. Ensure SDM harness connector is still connected. Disconnect VTD module harness connector. Turn ignition switch to RUN position. Attempt to communicate with any module on Class 2 serial data circuit. If scan tool does not communicate with other modules, go to next step. If scan tool communicates with other modules, go to step  23 .
  21. Ensure all modules are disconnected from Class 2 data line. Check for short to voltage or short to ground in Purple wire at DLC terminal No. 2. If there is a short, go to next step. If there is not a short, go to step  23 .
  22. Turn ignition switch to OFF position. Disconnect all harness connectors from driver side IP junction block. Remove all Class 2 data circuit (Purple wires) from driver side IP junction block harness connectors. See CONNECTOR IDENTIFICATION  . Connect driver side IP junction block harness connectors, without Class 2 circuit wires, to driver side IP junction block. Turn ignition switch to RUN position position. Test Class 2 data circuit wires, while out of driver side IP junction block harness connectors, for short to voltage or ground. Terminals with two modules connected to them may require separation to determine which wire is shorted. If fault is found, repair and go to step  24 . If no fault is found, go to step  1 .
  23. Replace last module that was disconnected. See appropriate procedure under REMOVAL & INSTALLATION  . After replacing module, go to next step.
  24. Turn ignition switch to OFF position. Disconnect scan tool. Reconnect all harness connectors. Connect scan tool to Data Link Connector (DLC). Reconnect scan tool. Turn ignition switch to RUN position. Wait 10 seconds. Scan tool may require a power up reset before communication will occur if Class 2 serial data line was shorted. Attempt to communicate with each module on Class 2 serial data line. If scan tool communicates with any module on Class 2 serial data line, go to next step. If scan tool does not communicate with any module on Class 2 serial data line, go to step  2 .
  25. Using scan tool, select DISPLAY DTCS function and retrieve DTCs from all modules on Class 2 serial data line. Record DTCs and DTC status. If DTCs not beginning with "U" with a current status are retrieved, go to next step. If any DTCs beginning with a "U" are retrieved with a current status, go to step  28 .
  26. On codes not beginning with "U", perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . After completing necessary repairs, go to next step.
  27. If all DTCs are diagnosed, go to next step. If all DTCs are not diagnosed, go to step  25 .
  28. Using scan tool, clear DTCs. System is okay at this time.
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