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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 C0327: Encoder 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 a voltage reading on the scan tool.
  2. 3:  This step tests the encoder circuit for a current malfunction.
  3. 4:  This step tests for an internal encoder malfunction which is present only in certain areas of the encoder sensor.
  4. 5:  This step tests for proper reference voltage at the encoder.
  5. 6:  This step tests the 5-volt reference circuit for proper voltage when the low reference circuit is used as a ground.
  6. 8:  This step tests the 5-volt reference encoder circuit for a short to voltage, short to ground, an open or high resistance.
  7. 9:  After determining that the reference voltage measured in Step 4 was correct, Step 6 reviews the reading originally measured in Step 3 to see if it was higher or lower than what should have been expected. This step helps determine whether the encoder signal circuit is being pulled high or low.
  8. 10:  This step tests the encoder signal circuit and the encoder low reference circuit for a short to voltage.
  9. 11:  This step helps determine a faulty encoder.
  10. 12:  This step tests the encoder signal circuit and the encoder low reference circuit for an open or a short to ground.
DTC C0327

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 - Vehicle? - 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. With a scan tool, observe the Encoder supply and return voltage parameters.
Are the voltage parameters displayed?		 - Go to Step 3  Go to Step 5 
3 
  1. Install a scan tool.
  2. Start the engine.
  3. Set the parking brake.
  4. Place the transmission in NEUTRAL.
  5. With a scan tool, observe the Encoder Return Voltage parameter in the Transfer Case Data List.
  6. Select each of the mode positions.
Does the voltage reading stay within the specified values?		 0.5-4.5 V Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 4 
4  Does the voltage reading stay within the specified values at any position? 0.5-4.5 V Go to Step 13  Go to Step 5 
5 
  1. Turn the ignition OFF.
  2. Disconnect the encoder motor.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure the voltage from the 5-volt reference encoder circuit to ground on the transfer case shift control module side of the harness.
Does the voltage measure within the specified values?		 4.8-5.2 V Go to Step 6  Go to Step 8 
6  Test the low reference circuit by jumping from the 5-volt reference circuit pin A to the low reference circuit pin C at the encoder pigtail on the module side of the harness.
Does the voltage reading stay within the specified values?		 4.8-5.2 V Go to Step 9  Go to Step 7 
7 Test the low reference circuit for an open or high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
8  Test the 5-volt reference encoder circuit for a short to voltage, short to ground, an open, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
9  Was the voltage reading measured in Step 4 greater than 5.2 volts? - Go to Step 10  Go to Step 11 
10  Test the encoder signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
11 
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. Using a fused jumper, backprobe between the 5-volt reference encoder circuit and encoder signal circuit on the transfer case shift control module side of the harness.
  4. With a scan tool, observe the Encoder Return Voltage parameter.
Is the encoder return voltage display within the specified values?		 4.8-5.2 V Go to Step 13  Go to Step 12 
12  Test the encoder signal circuit and the encoder low reference circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
13 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 15  -
14
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 incomplete programming or setting 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 15  -
15
  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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