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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 C0308 >> 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:  Listen for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.
  2. 3:  Tests for a short to ground in the Motor Control A circuit.
  3. 4:  Tests for a short to ground in the Motor Control B circuit.
  4. 5:  Tests for a higher than normal resistance in the Motor Control A and B circuits through the module.
  5. 6:  Tests for a short to ground in the encoder motor windings.
  6. 7:  Tests for continuity across the motor circuit. Resistance readings vary depending on the location of the brush contact inside the motor assembly.
  7. 8:  Tests Motor Feed A circuit for a short to ground.
  8. 9:  Tests Motor Feed B circuit for a short to ground.
  9. 10:  Tests Motor Feed A and B circuits for an open or high resistance.
DTC C0308 Motor A/B Circuit Low

Step Action Value(s) Yes No
Schematic Reference:  Transfer Case Control Schematics  
1 Was the Transfer Case Diagnostic System Check performed? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Check and replace the ATC fuse as necessary.
  2. Install a scan tool.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, command the Motor A/B control ON and OFF.
Does the encoder motor turn ON and OFF?		 - Go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS Go to Step 3 
3 
  1. Turn the ignition OFF.
  2. Disconnect the four wire connector at the transfer case.
  3. Connect a DMM between the Motor Control A circuit and ground at the transfer case connector.
Is the resistance reading less than the specified value?		 10 K Ω Go to Step 8  Go to Step 4 
4  Connect a DMM between the Motor Control B circuit harness connector and ground at the transfer case.
Is the resistance reading less than the specified value?		 10 K Ω Go to Step 9  Go to Step 5 
5  Connect a DMM between the Motor Control A and B circuit harness connector at the transfer case.
Is the resistance reading greater than the specified value?		 2 Ω Go to Step 10  Go to Step 6 
6 
IMPORTANT: The transfer case Motor Control circuits have capacitors connected between their circuit and ground. When making resistance checks with a DMM allow the reading to stabilize (approximately 10 seconds) before making the final measurement (as the capacitor charges it can give the indication of a short circuit).
Test terminals A and B at the transfer case side of the harness for a short to ground.Was a short to ground found?		 - Go to Step 11  Go to Step 7 
7  Test the resistance across the motor circuit.
Was the motor within the specified values.		 0.5-35 Ω Go to Step 12  Go to Step 11 
8 
  1. Disconnect the transfer case shift control module.
  2. Test the Motor Control A circuit for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 13  Go to Step 12 
9 
  1. Disconnect the transfer case shift control module.
  2. Test the Motor Control B circuit harness connector for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 13  Go to Step 12 
10 
  1. Disconnect the transfer case shift control module.
  2. Test the Motor Control A and B circuits for an open or high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 13  Go to Step 12 
11 Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement .
Is the repair complete?		 - Go to Step 13  -
12 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .
Is the repair complete?		 - Go to Step 13  -
13
  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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