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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Test for less than 1.0 ohm between the ground circuit terminal 5 of the DLC and ground.
    • If greater than the specified range, test the ground circuit for open/high resistance.
  2. Remove the terminator resistor.
  3. Test for 110-130 ohms between the terminals of the resistor.
    • If not within the specified range, replace the resistor.
  4. Connect the terminator resistor.
  5. Ignition OFF, disconnect the harness connector X3 at the BCM.
  6. Test for less than 2 ohms on the serial data circuit between terminal 6 of the DLC and terminal 16 of the BCM.
    • If greater than the specified range, test the serial data circuit for open/high resistance.
  7. Ignition OFF, disconnect the harness connector X4 of the BCM.
  8. Verify a test lamp illuminates between each ground circuit terminal of the BCM listed below and B+.
    • X3 terminal 1
    • X3 terminal 5
    • X4 terminal 9
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  9. Ignition ON, verify a test lamp illuminates between each B+ circuit terminal of the BCM listed below and ground.
    • X4 terminal 1
    • X4 terminal 3
    • X4 terminal 4
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
  10. Ignition OFF, disconnect the harness connector of the EBCM.
  11. Ignition ON, test for less than 1 volt between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground.
    • If greater than the specified range, test the serial data circuit for a short to voltage.
  12. Test for infinite resistance between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground.
    • If less than the specified value, test the serial data circuit for a short to ground.
  13. Test for infinite resistance between the serial data circuits terminal 6 and terminal 14 of the DLC.
    • If less than the specified value, test the serial data circuits for a short between them.
  14. Connect the harness connectors of the BCM and the EBCM.
  15. Disconnect the harness connector X3 of the ECM.
  16. Attempt to communicate with the suspension control module. Communication should not be available.
    • If communication is available, replace the ECM.
  17. Ignition OFF, disconnect the harness connector X1 of the TCM.
  18. Attempt to communicate with the suspension control module. Communication should not be available.
    • If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the TCM and the ECM. If the circuits test normal, replace the TCM.
  19. Ignition OFF, disconnect the harness connector of the EBCM.
  20. Attempt to communicate with the suspension control module. Communication should not be available.
    • If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the EBCM and the TCM. If the circuits test normal, replace the EBCM.
  21. Ignition OFF, connect the harness connectors of the EBCM, TCM, and ECM.
  22. Ignition OFF, disconnect the harness connector X2 of the suspension control module.
  23. Attempt to communicate with the EBCM. Communication should not be available.
    • If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the suspension control module and the terminator resistor. If the circuits test normal, replace the suspension control module.
  24. Ignition OFF, disconnect the harness connector of the distance sensing cruise control (DSCC) if equipped. Attempt to communicate with the EBCM. Communication should not be available.
    • If communication is available, replace the DSCC module.
  25. Ignition OFF, disconnect the harness connectors X1 and, X2 of the vehicle communication interface module (VCIM) if equipped. Attempt to communicate with the EBCM. Communication should not be available.
    • If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the VCIM and the suspension control module. If the circuits test normal, replace the VCIM.
  26. Ignition OFF, disconnect the harness connector X3 of the BCM.
  27. Ignition ON, test for less than 1 volt between the serial data circuits of BCM terminal 8 and ground, and between BCM terminal 9 and ground.
    • If greater than the specified range, test the circuit for a short to voltage.
  28. Test for infinite resistance between the serial data circuits of BCM terminal 8 and ground, and between BCM terminal 9 and ground.
    • If less than the specified value, test the circuit for a short to ground.
  29. Test for infinite resistance between the serial data circuits terminal 8 terminal 9 of the BCM.
    • If less than the specified VAlue, test the serial data circuits for a short between them.
  30. If the circuits test normal, replace the BCM.
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