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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 131 (Transfer Case - NVG 246-NP8) >> Diagnostic Information and Procedures >> DTC B0780 >> Test Description

Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step looks for the visual operation of the 4LO indicator. Command both the ON and OFF states.
  2. 3:  This step helps determine if proper voltage is supplied to the transfer case select switch.
  3. 4:  This step helps determine if there is a short to ground in the indicator control circuit.
  4. 5:  This step helps determine if there is an open in the indicator control circuit.
  5. 6:  This step tests the indicator feed circuit for an open or high resistance.
  6. 7:  This step tests the 4LO neutral control circuit for a short to ground.
  7. 8:  This step tests the 4LO neutral control circuit for an open or high resistance.
DTC B0780

Step Action Yes No
Schematic Reference:  Transfer Case Control Schematics  
Connector End View Reference:  Transfer Case Control Connector End Views  
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. With the scan tool, command the 4LO indicator control ON and OFF.
Does the 4LO neutral turn ON and OFF with each command?		 Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3  With a scan tool, command the AWD, 4HI, and 2HI indicators ON and OFF.
Do all the indicators turn ON and OFF?		 Go to Step 4  Go to Step 6 
4  Does the 4LO indicator stay ON? Go to Step 7  Go to Step 5 
5 
  1. Remove the transfer case select switch.
  2. While the transfer case select switch is still connected to the harness, backprobe the 4LO indicator control circuit with a wire to a good ground.
Does the 4LO neutral illuminate?		 Go to Step 8  Go to Step 9 
6  Test the LED dimming supply circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 11  Go to Step 9 
7  Test the 4LO indicator control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 11  Go to Step 10 
8  Test the 4LO indicator control circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 11  Go to Step 10 
9 Replace the transfer case select switch. Refer to Transfer Case Shift Control Switch Replacement .
Did you complete the repair?		 Go to Step 11  -
10
IMPORTANT: After transfer case shift control module replacement and reprogramming, ensure all doors are closed and the key is out of the ignition, then open and close the doors again and wait 2 minutes to avoid incomplete programming or false communication DTCs.
Replace the transfer case shift control module. Refer to Control Module References for replacement, setup, and programming. Perform the Clutch Reset Procedure. Refer to Transfer Case High/Low Clutch Reset .Did you complete the repair?		 Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 Go to Step 2  System OK
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