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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 359 (Transfer Case - Mp 3010-NP0) >> Diagnostic Information and Procedures >> DTC B0785 >> Component Testing

Component Testing

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BCM

  1. Key OFF. Disconnect the X1 connector at the TCSCS.
  2. Using the L-BU probe J 35616-64B, connect a test light between the indicator dimming control circuit, TCSCS harness X1 pin 4 and a good ground.
  3. Key ON, engine OFF. The test light should be dull or OFF.
    • If the test light is bright, test the indicator dimming control circuit for a short to voltage condition. If all circuits and connections test normal, replace the BCM.
    4. NOTE:

    When the DRL sensor turns the headlights OFF, the indicator dimming control circuit voltage, TCSCS X1 pin 4, will go from a diagnostic B+ to a true B+.

  4. Place a shop light on the DRL sensor. When the headlights go out the test light should illuminate brightly.

TCCM

  1. Key OFF. Disconnect the X1 connector at the TCSCS.
  2. Key ON, engine OFF.
  3. Using the L-BU probe J 35616-64B, test for 4.5-5.5 V between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground.
    • If the voltage is greater than the specified range, test the 5-volt reference circuit for a short to voltage. If all circuits and connections test normal, replace the TCCM.
    • If the voltage is less than the specified range, test the 5-volt reference circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCCM.
  4. Using the L-BU probe J 35616-64B, connect a test light between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground. The test light should illuminate dimly.
    • If the test light does not illuminate, obtain a different test light and repeat step 4.
  5. Key OFF. Wait 30 seconds for the TCCM to shut down.
    6. NOTE:

    The TCCM must see the added resistance of the test light on the control circuit at key ON or the TCCM will shut the control circuit drivers OFF. Volt meters will not work for this test.

  6. Using the L-BU probe J 35616-64B, connect a test light between the TCSCS harness as specified below for the LED control circuit being tested.
  7. Key ON, engine OFF.
  8. Using the Special Function ability of the scan tool, command the affected LED ON and OFF. The test light should turn ON and OFF as commanded.
    • If the test light remains illuminated when commanded OFF, test the affected control circuit for a short to ground. If all circuits and connections test normal, replace the TCCM.
    • If the test light remains OFF when commanded ON, test the affected control circuit for an open/high resistance or short to voltage. If all circuits and connections test normal, replace the TCCM.
Mode 2 High 4WD Auto 4 High
5 V Reference (pin) 11 11 11
Indicator Control Circuit (pin) 8 7 9

TCSCS

  1. Using the L-BU probe J 35616-65B, connect the memory saver EL-49741  harness to the TCSCS as specified below for the LED being tested. Connecting the harness to the opposite pins will not illuminate the LED.
  2. Connect a 9 V battery to the memory saver EL-49741  harness.
  3. Verify that only the indicator being tested illuminates.
    • If the indicator does not illuminate when tested or the incorrect indicator illuminates, replace the TCSCS.
EL49741 Wire Color 2 High 4WD Auto 4 High
Red (pin) 4 4 4
Black (pin) 8 7 9
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