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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 113 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT COMMUNICATE WITH HIGH SPEED GMLAN DEVICECIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Circuit/System Testing

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Chevrolet Malibu Classic. 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. Ignition OFF, disconnect the X2 harness connector at the BCM.
  3. Test for less than 2 ohms on the serial data circuit between terminal 6 of the DLC and terminal 1 of the BCM.
    • If greater than the specified range, test the serial data circuit for open/high resistance.
  4. Ignition OFF, disconnect the X3 and X4 harness connector at the BCM.
  5. Verify a test lamp illuminates between each ground circuit terminal of the BCM listed below and B+.
    • X2 terminal 13
    • X3 terminal 12
    • X4 terminal E12
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  6. Ignition ON, verify a test lamp illuminates between each B+ circuit terminal D12 of the BCM and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
  7. 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.
  8. 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.
  9. 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.
  10. Connect the X2 X3 and X4 harness connectors at the BCM.
  11. Disconnect the appropriate harness connector at the ECM.
    • RPO L61 - X1
    • RPO LZ4/LZ9 - X1
    • RPO LY7/LE5 - X3
  12. Attempt to communicate with the vehicle control interface module (VCIM). Communication should not be available.
    • If communication is available, replace the ECM.
  13. Ignition OFF, disconnect the harness connector at the TCM.
  14. Attempt to communicate with the VCIM. Communication should not be available.
    • If communication is available, test the following 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.
      • RPO LY7 - 12
      • RPO LY7 - 5
      • RPO LY7 - 5 and 12
      • RPO LZ4/LZ9/LE5 - 37
      • RPO LZ4/LZ9/LE5 - 38
      • RPO LZ4/LZ9/LE5 - 37 and 38
  15. Ignition OFF, disconnect the harness connector at the EBCM.
  16. Attempt to communicate with the VCIM. Communication should not be available.
    • If communication is available, test the following 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.
      • B12
      • B9
  17. Ignition OFF, disconnect the X2 harness connector at the power steering control module.
  18. Attempt to communicate with the VCIM. Communication should not be available.
    • If communication is available, test the following 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 power steering control module.
      • 1
      • 2
  19. Ignition OFF, disconnect the X3 harness connector at the VCIM. Attempt to communicate with the BCM. Communication should not be available.
    • If communication is available, test the following 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.
      • 9
      • 8
  20. Ignition OFF, disconnect the X2 harness connector at the BCM.
  21. Ignition ON, test for less than 1 volt between the following serial data circuits of BCM and ground.
    • 20
    • 2
    • If greater than the specified range, test the circuit for a short to voltage.
  22. Test for infinite resistance between the following serial data circuits of BCM and ground.
    • 20
    • 2
    • If less than the specified value, test the circuit for a short to ground.
  23. Test for infinite resistance between the serial data circuits terminal 20 terminal 2 of the BCM.
    • If less than the specified Value, test the serial data circuits for a short between them.
  24. If the circuits test normal, replace the BCM.
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