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Checking Data Bus Communication

  1. Check all module harness connectors for proper connection. Perform Function Mode 00 (automatic test sequence). See ENTERING ON-BOARD DIAGNOSTIC FUNCTION MODES  under SELF-DIAGNOSTIC SYSTEM. All modules with rapid data transfer capability will respond with its identification and display stored DTCs or error messages.
  2. If any data bus or no communication DTCs are stored for one or more modules, go to next step. If all modules are not sending or receiving data, go to step  4 .
  3. Ensure malfunctioning module has correct part number and coding. If part number and coding are correct, disconnect all modules in circuit. Check for open data bus between modules. See WIRING DIAGRAMS  . Repair as necessary. If circuits are okay, replace malfunctioning module.
  4. Disconnect all modules in circuit. Check data bus for short to ground, short to voltage or short between bus wires. See WIRING DIAGRAMS  . Repair as necessary. If circuits are okay, reconnect one module, and leave other modules disconnected. Clear DTCs for reconnected module. See FUNCTION MODE 05: ERASING DTC MEMORY  .
  5. Exit on-board diagnostics. See FUNCTION MODE 06: EXITING ON-BOARD DIAGNOSTICS  . Turn ignition off then on. Wait 10 seconds, then retrieve DTCs for reconnected module. If DATA BUS FAULTY message is displayed, replace reconnected module. If no DTCs or error messages are displayed, repeat step  4 using next disconnected module.
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