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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 C0321: Transfer Case Lock Circuit >> 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 listens for an audible click when the encoder motor brake operates. Command both the ON and OFF states. Repeat the commands as necessary.
  2. 3:  This step tests for voltage at the lock solenoid feed side of the encoder motor lock solenoid.
  3. 4:  This step verifies that the lock solenoid battery positive circuit is not shorted to power, shorted to ground or has high resistance.
  4. 5:  This step determines if the encoder motor lock solenoid is faulty by checking the internal resistance.
  5. 6:  This step tests the control circuit of the encoder motor brake for a short to voltage or an open.
  6. 7:  This step determines if a corroded or damaged connector in the encoder motor harness is the cause.
DTC C0321

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. Turn the ignition ON, with the engine OFF.
  3. Apply the parking brake.
  4. Place the transmission in NEUTRAL.
  5. With the scan tool, command the transfer case lock control ON and OFF.
Does the encoder motor lock turn ON and OFF with each command?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 
  1. Turn the ignition ON, with the engine OFF.
  2. Using a DMM, measure the battery positive voltage circuit of the transfer case lock solenoid.
Is the voltage within the specified range?		 12.5-14.5 Go to Step 5  Go to Step 4 
4  Inspect the lock solenoid battery positive circuit for open, 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 10  Go to Step 5 
5 
  1. Disconnect the transfer case encoder motor connector.
  2. Check the internal resistance of the lock solenoid.
Is the resistance within the specified values?		 15-25 Ω Go to Step 6  Go to Step 8 
6 
  1. Disconnect the transfer case shift control module.
  2. Using a DMM, test the lock solenoid control circuit for and short to ground, short to voltage or high resistance.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
7  Check all connectors for corrosion or damage. Refer to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 9 
8 Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement (TrailBlazer, Envoy, Rainier, Bravada)  or Transfer Case Motor/Encoder Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV)  .
Did you complete the repair?		 - Go to Step 10  -
9
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 setting false 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 10  -
10
  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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