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DTC U2103: Fewer Controllers On Bus Than Programmed: Testing

  1. Perform appropriate diagnostic system check. See appropriate ENGINE PERFORMANCE article for ECM, appropriate AUTOMATIC TRANSMISSION article for TCM and appropriate ANTI-LOCK BRAKE/TRACTION CONTROL article for EBTCM. After performing diagnostic system check, go to next step.
  2. If DTC U2100 is recorded as a current or history code in ECM, EBTCM or TCM, go to U2100: CAN-BUS COMMUNICATION MALFUNCTION  . If DTC U2100 is not recorded as a current or history code in ECM, EBTCM or TCM, go to next step.
  3. If DTC U2105, U2106 or U2108 is recorded as a history code in ECM, EBTCM or TCM, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform diagnostic test for that DTC. If DTC U2105, U2106 or U2108 is not recorded as a history code in ECM, EBTCM or TCM, go to next step.
  4. Turn ignition off. Install scan tool to DLC. Turn ignition on. Using scan tool, select data display for ECM, EBTCM and TCM. Observe data parameters listed in DIAGNOSTIC AIDS  for missing data. If any module is not receiving data on CAN bus, go to next step. If all modules are receiving data on CAN bus, go to step  12 .
  5. Disconnect electrical harness connector from module that set DTC U2103. Inspect harness connector for poor terminal contact, corrosion and damage. See PRELIMINARY INSPECTION  under TROUBLE SHOOTING. If fault is located and repaired, go to step  8 . If fault is not located and repaired, go to next step.
  6. Disconnect electrical harness connector(s) from module(s) that are not communicating data on CAN bus circuit. Inspect harness connector(s) for poor terminal contact, corrosion and damage. See PRELIMINARY INSPECTION  under TROUBLE SHOOTING. If fault is located and repaired, go to step  8 . If fault is not located and repaired, go to next step.
  7. Replace and program module(s) not communicating data on the CAN bus circuit. See appropriate ENGINE PERFORMANCE article in ENGINE PERFORMANCE for ECM. See appropriate AUTOMATIC TRANSMISSION article in AUTOMATIC TRANSMISSIONS for TCM. See appropriate ANTI-LOCK/TCS article in BRAKES for EBTCM. After replacement, go to step  10 .
  8. Turn ignition off. Reconnect all disconnected electrical harness connectors. Install scan tool to DLC. Turn ignition on. Using scan tool, select display DTCs for module(s) not communicating data. If scan tool displays any DTCs other than U2100, U2103, U2104, U2105, U2106 or U2108, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform diagnostic test for that DTC. If scan tool does not display any DTCs other than U2100, U2103, U2104, U2105, U2106 or U2108, go to next step.
  9. Using scan tool, clear DTCs. See CLEARING DTCS  under SELF-DIAGNOSTIC SYSTEM. After clearing DTCs, go to next step.
  10. Using scan tool, select display DTCs for module(s) that had set a current DTC U2103. If scan tool displays any DTCs other than U2100, U2103, U2104, U2105, U2106 or U2108, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform diagnostic test for that DTC. If scan tool does not display any DTCs other than U2100, U2103, U2104, U2105, U2106 or U2108, go to next step.
  11. Using scan tool, clear DTCs. See CLEARING DTCS  under SELF-DIAGNOSTIC SYSTEM. After clearing DTCs, system should be okay.
  12. If any other DTCs were recorded for module(s) that had set a current DTC U2103, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform diagnostic test for that DTC. If no other DTCs were recorded by module(s) that had set a current DTC U2103, go to next step.
  13. Turn ignition off. Connect scan tool. Using scan tool, clear DTCs. Turn ignition off for at least 5 seconds. Turn ignition on. Select display DTCs. See BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If DTC U2103 is present as a current code, go to next step. If DTC U2103 is not present as a current code, system should be okay.
  14. Replace module(s) that had DTC U2103 set as a current code. See appropriate ENGINE PERFORMANCE article in ENGINE PERFORMANCE for ECM. See appropriate AUTOMATIC TRANSMISSION article in AUTOMATIC TRANSMISSIONS for TCM. See appropriate ANTI-LOCK/TCS article in BRAKES for EBTCM. After replacement, system should be okay.
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