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DTC U1000: Loss Of Class 2 Serial Data Fault: Testing

  1. If body function controller (BFC) diagnostic system check has been performed, go to next step. If body function controller (BFC) diagnostic system check has not been performed, go toBODY FUNCTION CONTROLLER (BFC) DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  2. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to RUN position. Note all modules communicating over class 2 serial data line. Using scan tool, establish communication with all modules along class 2 serial data line. If communication cannot be established with all modules, go to next step. If communication can be established with all modules, go to step  11 .
  3. Check for open, poor connections or short to ground in power circuits for non-communicating module. See appropriate wiring diagram in POWER DISTRIBUTION article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to step  9 . If circuit is okay, go to next step.
  4. Turn ignition switch to LOCK position. Check for open or poor connections in ground circuits for non-communicating module. See appropriate wiring diagram in GROUND DISTRIBUTION article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to step  9 . If circuit is okay, go to next step.
  5. Check for poor connections at battery voltage, ground and class 2 serial data circuits of non-communicating module. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to step  7 . If circuit is okay, go to next step.
  6. Replace module not communicating with class 2 serial data line. See appropriate removal and installation procedure for corresponding module. After repairs, go to step  9 .
  7. Connect scan tool to DLC. Turn ignition switch to RUN position. Display DTCs for module not communicating. If any communication DTCs (communication DTCs begin with "U") are present, perform appropriate test under DIAGNOSTIC TESTS. See BFC DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If no communication DTCs are present, go to next step.
  8. Using scan tool, clear all DTCs. Go to next step.
  9. Using scan tool, display DTCs for module that had DTC U1000 set as current. If scan tool shows any DTCs that do not begin with "U", go to appropriate diagnostic and repair procedure for DTCs indicated. See BFC DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not show any additional DTCs, go to next step.
  10. Using scan tool, clear all DTCs. Go to BODY FUNCTION CONTROLLER (BFC) DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  11. Display DTCs for modules that had DTC U1000 set as current. If scan tool shows any additional DTCs, go to appropriate diagnostic and repair procedure for DTCs indicated. See BFC DTC DEFINITIONS  table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not show any additional DTCs, go to next step.
  12. Clear DTCs. Turn ignition switch to LOCK position for a minimum of 5 minutes. Turn ignition switch to RUN position. Check for DTCs. If DTC U1000 exists, go to next step. If DTC U1000 does not exist, go to BODY FUNCTION CONTROLLER (BFC) DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  13. Replace module not communicating with class 2 serial data line. After repairs, perform BODY FUNCTION CONTROLLER (BFC) DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
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