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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1435 (Transfer Case - NVG 226-NP8) >> Diagnostic Information and Procedures >> DTC B2725: ATC Mode Switch Circuit Malfunction >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. 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 the switch signal wire for a short to ground, short to voltage or high resistance.
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. Connect a DMM between the selector mode switch signal and voltage from the 5 volt reference circuit at the switch.
  2. Measure the resistance through the mode switch while selecting the modes and comparing values.
Does the DMM indicate all resistance values within the specified ranges?		 2 HI: 230-245 Ω
AWD: 526-580 Ω
4 HI: 1,042-1,107 Ω
4 LO: 2,039-2,165 Ω
Neutral: 4,467-4,743 Ω		 Go to Step 4  Go to Step 5 
4  Test the switch signal for a short to voltage, short to ground, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 7  Go to Step 6 
5 Replace the selector mode switch. Refer to Transfer Case Shift Control Switch Replacement (GMC, Buick)  or Transfer Case Shift Control Switch Replacement (Chevrolet)  .
Did you complete the repair?		 - Go to Step 7  -
6
IMPORTANT: After transfer case shift control module replacement and reprogramming make sure 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 Transfer Case Shift Control Module Replacement and Transfer Case Control Module Reprogramming  .Did you complete the repair?		 - Go to Step 7  -
7
  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 set?		 - Go to Step 2  System OK
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