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Home >> Chevrolet >> 2004 >> Avalanche 2500 >> Repair and Diagnosis >> External Pages >> Different car >> Section 411 (Transfer Case - BW 4482-Nr4) >> Diagnostic Information and Procedures >> DTC B2725: Active Transfer Case (ATC) Mode Switch Circuit >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Yukon XL and 2004 GMC Yukon. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  This step tests for proper operation of the transfer case mode select switch.
  2. 3:  This step tests the mode switch for proper resistance values in all mode switch states.
  3. 4:  This step tests for proper voltage on the 5-volt reference circuit.
  4. 5:  This step tests the 5-volt reference circuit for an open, high resistance, short to voltage, or short to ground.
  5. 6:  This step tests the switch signal circuit for an open, high resistance, short to voltage, or short to ground.
DTC B2725

Step Action Values 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 - Transfer Case? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Install a scan tool.
  2. Start the engine.
  3. Set the parking brake.
  4. Place the transmission into Neutral.
  5. With a scan tool, observe the 4WD indicator modes in the tech 2 transfer case data list.
  6. Select each of the modes.
Does the scan tool indicate that the 4WD indicators are in the correct state?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 
  1. Disconnect and remove the mode switch.
  2. Connect a DMM between the switch signal and the 5-volt reference pins on the switch.
  3. Measure the resistance through the mode switch while pressing and holding each of the mode buttons and comparing values.
Does the DMM indicate all resistance values within the specified ranges?		 TCS: 1.50-1.53K Ω
AWD: 656.2-669.4 Ω
Neutral: 1.010-1.031K Ω
Normal: 9-9.18K Ω		 Go to Step 4  Go to Step 7 
4  Check the voltage on the 5-volt reference circuit.
Was the voltage within the specified range?		 4.8-5.1 V Go to Step 6  Go to Step 5 
5  Test the 5-volt reference circuit for an open, short to ground, short to voltage, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 9  Go to Step 8 
6  Test the switch signal circuit for a short to voltage, short to ground, open, or high resistance. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 9  Go to Step 8 
7 Replace the mode switch. Refer to Transfer Case Shift Control Switch Replacement .
Did you complete the repair?		 - Go to Step 9  -
8 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement 
Did you complete the repair?		 - Go to Step 9  -
9
  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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