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Diagnostic 1

WARNING: This page is about a different car, the 2008 Cadillac XLR. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X2 harness connector at the BCM.
  2. Ignition OFF, test for less than 2 ohms of resistance between the DLC serial data circuit terminal 6 and BCM serial data circuit terminal 1.
    • If greater than the specified range, test the serial data circuit for open/high resistance.
  3. Ignition OFF, disconnect the X1 and X4 harness connectors at the BCM.
  4. Test for less than 5 ohms of resistance between the following ground circuit terminals and ground.
    • X1 terminal 12
    • X4 terminal E12
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  5. Ignition OFF, disconnect the X3 harness connectors at the BCM.
  6. Ignition ON, verify a test lamp illuminates between the following B+ circuit terminals and ground.
    • X3 terminal D12
    • X3 terminal D1
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the B+ output circuits for a short to ground.
  7. Ignition OFF, test for infinite resistance between the following serial data circuits of the DLC and ground.
    • Terminal 6
    • Terminal 14
    • If less than the specified value, test the serial data circuits for a short to ground.
  8. Ignition ON, test for less than 1 volt between the following serial data circuits of the DLC and ground.
    • Terminal 6
    • Terminal 14
    • If greater than the specified range, test the serial data circuit for a short to voltage.
  9. Ignition OFF, test for infinite resistance between the DLC serial data circuit terminal 6 and terminal 14.
    • If less than the specified value, test for a short between the serial data circuits.
  10. Connect the X1, X2, X3 and X4 harness connector at the BCM.
  11. Ignition OFF, disconnect the harness connector at the ESC module.
  12. Ignition ON, attempt to communicate with the VCIM. Communication should not be available.
    • If communication is established, test the following serial data circuits between the ESC module and the TECH for a short between the circuits, short to ground or a short to voltage. If the circuits test normal, replace the ESC module.
      • Terminal 40
      • Terminal 22
  13. Ignition OFF, disconnect the X4 harness connector at the VCIM if applicable.
  14. Ignition ON, attempt to communicate with the ACM. Communication should not be available.
    • If communication is established, test the following serial data circuits between the VCIM and the ESC module for a short between the circuits, short to ground or a short to voltage. If the circuits test normal, replace the VCIM.
      • Terminal 2
      • Terminal 3
      • Terminal 2 and 3
  15. Ignition OFF, disconnect the harness connector at the ACM.
  16. Ignition ON, attempt to communicate with the BCM. Communication should not be available.
    • If communication is established, test the following serial data circuits between the ACM and the VCIM for a short between the circuits, short to ground or a short to voltage. If the circuits test normal, replace the ACM.
      • Terminal 9
      • Terminal 8
      • Terminal 9 and 8
  17. Ignition OFF, disconnect the X2 harness connector at the BCM.
  18. Ignition OFF, test for infinite resistance between the following serial data circuits and ground.
    • Terminal 2
    • Terminal 20
    • If less than the specified value, test the serial data circuit for a short to ground.
  19. Ignition ON, test for less than 1 volt between the following serial data circuits and ground.
    • Terminal 2
    • Terminal 20
    • If greater than the specified range, test the serial data circuit for a short to voltage.
  20. Ignition OFF, test for infinite resistance between the serial data circuit terminal 2 and terminal 20.
    • If less than the specified value, test for a short between the serial data circuits.
  21. If the circuits test normal, replace the BCM.
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