LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 997 (Transfer Case - NVG 246-NP8) >> Diagnostic Information and Procedures >> DTC C0374: General System Malfunction >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. 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 determines if the rear propshaft speed sensor and wiring are operating properly.
  2. 3:  This step determines if the front propshaft speed sensor and wiring are operating properly.
  3. 4:  This step determines if the motor control A or motor control B circuits are shorted to ground within the encoder motor.
  4. 5:  This step tests the integrity of the motor windings.
  5. 6:  This step tests the motor control A and motor control B circuits for an open, short to ground, or high resistance between the encoder motor and the transfer case shift control module.
  6. 7:  This step determines whether the transfer case is mechanically functioning properly.
DTC C0374

Step Action Value(s) 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. Take the vehicle for a short test drive.
  2. With the scan tool, observe the Rear Propshaft Speed data parameter in the Transfer Case Data List while driving.
Does the RPM value vary or become intermittent while driving at a steady speed?		 - Go to DTC C0300  Go to Step 3 
3 
  1. Take the vehicle for a short test drive.
  2. Observe the scan tool Front Propshaft Speed data parameter in the Transfer Case Data List, while driving.
Does the RPM value vary or become intermittent while driving?		 - Go to DTC C0305  Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Disconnect the encoder motor connector.
  3. With a DMM at the encoder motor pigtail connector, test motor control A and motor control B for a short to ground within the encoder motor.
Is motor control A or motor control B shorted to ground?		 - Go to Step 9  Go to Step 5 
5 
IMPORTANT: Use test leads designed for this connector and make firm contact with the leads.
  1. Turn OFF the ignition.
  2. Zero the DMM, with ohms selected, by touching the two leads.
  3. Connect the DMM between motor control A terminal and motor control B terminal and test the resistance in the encoder motor.
Is the encoder motor within the specified values?		 0.3 - 35 Ω Go to Step 6  Go to Step 9 
6  Test the motor A and motor B control circuits for a short to ground, short to voltage, open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 11  Go to Step 7 
7 
  1. Remove the encoder motor assembly. Refer to Transfer Case Encoder Motor Replacement .
  2. Connect a wrench to the transfer case sector shaft.
  3. Turn the shift lever detent shaft to apply the clutch pack.
  4. While the clutch pack is applied, attempt to turn the front propshaft using a pry bar between the front propshaft U-Joint.
Does the clutch hold the propshaft and prevent it from being turned?		 - Go to Step 9  Go to Step 8 
8 Remove the transfer case and overhaul. Refer to Transfer Case Disassemble in Transfer Case - NVG 246-NP8 Unit Repair.
Did you complete the repair?		 - Go to Step 11  -
9 Replace the transfer case encoder motor. Refer to Transfer Case Encoder Motor Replacement .
Did you complete the repair?		 - Go to Step 11  -
10 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 2  -
11
  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 10  System OK
scientia non olet · About LEMON Manuals