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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1316 (Transfer Case - NVG 246-NP8 (Two Speed Automatic)) >> Diagnostic Information and Procedures >> DTC C0374 >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. 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:  Helps determine if the DTC set due to a mechanical or an electrical fault.
  2. 3:  Tests the integrity of the Motor Control circuit.
  3. 4:  Determines whether the Encoder Motor is moving to the proper position.
DTC C0374

Step Action Yes No
Schematic Reference:  Transfer Case Control Schematics  
1
IMPORTANT: If DTC C0300 or C0305 is also present perform the diagnostic for these DTCs before continuing.
Was the Transfer Case Diagnostic System Check performed?		 Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Place the transmission in PARK
  2. Turn the ignition ON, with the engine OFF.
  3. Install a scan tool.
  4. Clear all ATC DTCs.
  5. Use the scan tool in order to command the Encoder Motor A and B ON.
Is the Encoder Motor turning on (buzzing noise)?		 Go to Step 4  Go to Step 3 
3 
  1. Turn the ignition OFF.
  2. Disconnect the encoder motor.
  3. Turn the ignition ON, with the engine OFF.
  4. Cycle the transfer case between 2WD and 4WD.
  5. Use the scan tool to check for DTCs.
Did DTC C0310 set?		 Go to Step 6  Go to Step 7 
4 
  1. Using the scan tool device control for the ATC Mode Switch, manually command the transfer case gear positions.
  2. Use the Increase and Decrease buttons on the scan tool to command through all the ATC Mode Switch states while observing the Encoder Gear Position parameter.
Does the Encoder Gear Position parameter state change as commanded by the scan tool?		 Go to Step 5  Go to Step 6 
5 Remove the transfer case and overhaul.
Is the repair complete?		 Go to Step 8  -
6 Replace the transfer case encoder motor. Refer to Transfer Case Motor/Encoder Replacement .
Is the repair complete?		 Go to Step 8  -
7 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .
Is the repair complete?		 Go to Step 8  -
8
  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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