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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

High Speed GMLAN Initial Test

  1. Test for less than 1.0 ohm of resistance between the DLC ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  2. Disconnect the X200 inline harness connector at the DLC.
  3. Ignition ON, attempt to communicate with the fuel system control module.
    • If communication is established refer to DIAGNOSTIC 2.
    • If communication is not established, refer to DIAGNOSTIC 1.

DIAGNOSTIC 1

  1. Connect the X200 inline harness connector.
  2. Remove the 120 ohm terminator resistor.
  3. Test for 108-132 ohms of resistance between terminals A and B of the terminator resistor.
    • If not within the specified range, replace the resistor.
  4. Connect the harness connector at the terminator resistor.
  5. Ignition OFF, disconnect the X3 harness connector at the BCM.
  6. Ignition OFF, test for less than 2 ohms of resistance between the DLC serial data circuit terminal 6 and BCM serial data circuit terminal 8.
    • If greater than the specified range, test the serial data circuit for open/high resistance.
  7. Ignition OFF, disconnect the X2 and X4 harness connectors at the BCM.
  8. Test for less than 5 ohms of resistance between the following ground circuit terminals and ground.
    • X3 terminal 1
    • X3 terminal 5
    • X4 terminal 9
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  9. Ignition ON, verify a test lamp illuminates between the following B+ circuit terminals and ground.
    • X2 terminal 2
    • X3 terminal 2
    • X3 terminal 3
    • X4 terminal 1
    • X4 terminal 2
    • X4 terminal 3
    • X4 terminal 4
    • X4 terminal 10
    • 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.
  10. 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.
  11. 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.
  12. 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.
  13. Connect the X2, X3 and X4 harness connector at the BCM.
  14. Ignition OFF, disconnect the harness connector at the rear differential clutch control module.
  15. Ignition ON, attempt to communicate with the EBCM. Communication should not be available.
    • If communication is established, replace the rear differential clutch control module.
  16. Ignition OFF, disconnect the harness connector at the fuel system control module.
  17. Ignition ON, attempt to communicate with the EBCM. Communication should not be available.
    • If communication is established, remove the terminator resistor and test the following serial data circuits between the fuel system control module and the terminator resistor and the fuel system control module and the rear differential clutch control module for a short between the circuits, short to ground or a short to voltage. If the circuits test normal, replace the fuel system control module.
      • Fuel system control module terminal 21
      • Fuel system control module terminal 22
      • Fuel system control module terminal 21 and 22
      • Terminator resistor terminal A
      • Terminator resistor terminal B
      • Terminator resistor terminal A and B
  18. Ignition OFF, disconnect the X1 and X2 harness connector of the vehicle communication interface module (VCIM).
  19. Ignition ON, attempt to communicate with the EBCM. 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 3
      • Terminal 4
  20. Ignition OFF, disconnect the X1 harness connector at the electronic power steering (EPS) module
  21. Ignition ON, attempt to communicate with the EBCM. Communication should not be available.
    • If communication is established, test the following serial data circuits between the EPS module and the VCIM 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 8
  22. Ignition OFF, disconnect the X3 harness connector at the BCM.
  23. Ignition OFF, test for infinite resistance between the following serial data circuits and ground.
    • Terminal 17
    • Terminal 16
    • If less than the specified value, test the serial data circuit for a short to ground.
  24. Ignition ON, test for less than 1 volt between the following serial data circuits and ground.
    • Terminal 16
    • Terminal 17
    • If greater than the specified range, test the serial data circuit for a short to voltage.
  25. Ignition OFF, test for infinite resistance between the serial data circuit terminal 16 and terminal 17.
    • If less than the specified value, test for a short between the serial data circuits.
  26. If the circuits test normal, replace the BCM.

DIAGNOSTIC 2

  1. Connect the X200 inline harness connector.
  2. Ignition OFF, disconnect the appropriate harness connector listed below at the ECM.
    • RPO LY7, LZ4, or LE5 - X1
    • RPO HP7 - X3
  3. Ignition ON, attempt to communicate with the EPS module. Communication should not be available.
    • If communication is established, replace the ECM.
  4. Ignition OFF, disconnect the harness connector at the TCM if applicable.
  5. Ignition ON, attempt to communicate with the EPS module. Communication should not be available.
    • If communication is established, test the following serial data circuits between the ECM and the TCM for a short between the serial data circuits, short to ground or a short to voltage. If the circuits test normal replace the TCM.
      • RPO MH2 or MH4 - terminal 2
      • RPO MH2 or MH4 - terminal 12
      • RPO MH2 or MH4 - terminal 2 and 12
      • RPO MN5 - terminal 37
      • RPO MN5 - terminal 38
      • RPO MN5 - terminal 37 and 38
      • RPO ME7 - terminal 6
      • RPO ME7 - terminal 7
      • RPO ME7 - terminal 6 and 7
  6. Ignition OFF, disconnect the harness connector at the EBCM.
  7. Ignition ON, attempt to communicate with the EPS module. Communication should not be available.
  8. If communication is established, test the following serial data circuits between the EBCM and the TCM for a short between the serial data circuits, short to ground or a short to voltage.
    • Terminal 12
    • Terminal 13
    • If the circuits test normal replace the EBCM.
  9. Ignition OFF, test for infinite resistance between the following serial data circuits of EBCM and ground.
    • Terminal 11
    • Terminal 14
    • If less than the specified value, test the serial data circuit for a short to ground.
  10. Ignition ON, test for less than 1 volt between the following serial data circuits of EBCM and ground.
    • Terminal 11
    • Terminal 14
    • If greater than the specified range, test the serial data circuit for a short to voltage.
  11. Ignition OFF, test for infinite resistance between the serial data circuit terminal 11 and terminal 14.
    • If less than the specified value, test for a short between the serial data circuits.
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