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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Transfer Case - NVG 246-NP8 - Service & Diagnosis) >> Diagnostic Information and Procedures >> DTC C0305 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests to see if the malfunction is intermittent.
  2. 3:  This step tests the internal resistance of the propshaft speed sensor.
  3. 4:  This step tests to see if the propshaft speed sensor can generate a sufficient amount of AC voltage.
  4. 5:  This step tests the front speed sensor low signal circuit for a short to ground, a high resistance, or an open.
  5. 6:  This step tests the front speed sensor high signal circuit for a short to ground, a high resistance or an open.
  6. 7:  This step tests the front speed sensor low signal circuit for a short to voltage.
  7. 8:  This step tests the front speed sensor high signal circuit for a short to voltage.
  8. 9:  This step tests the front speed sensor low signal circuit for a short to the front speed sensor high circuit.
DTC C0305

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 - Vehicle
2
  1. Place the transfer case in AUTO 4WD mode.
  2. Drive the vehicle for a short test drive.
  3. While driving at a steady speed, use a scan tool in order to observe the value of the Front Propshaft Speed parameter.
Does the RPM value vary or become intermittent while driving at a steady speed?		 - Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3
  1. Turn the ignition OFF.
  2. Disconnect the transfer case front propshaft speed sensor.
  3. Measure the resistance of the transfer case front propshaft speed sensor.
Is the resistance reading within the specified values?		 1,300-2,700 Ω Go to Step 4  Go to Step 10 
4
  1. Connect a DMM to the transfer case front propshaft speed sensor.
  2. Block the front wheels.
  3. Place the transmission in Neutral.
  4. Raise and support the vehicle so that the wheels turn freely. Refer to Lifting and Jacking the Vehicle .
  5. Hold one front wheel while rotating the other front wheel.
  6. Observe the AC voltage reading on the DMM.
Is the voltage reading greater than the specified value?		 0.5 V AC Go to Step 5  Go to Step 10 
5
  1. Disconnect the transfer case shift control module.
  2. Test the front speed sensor low signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 6 
6 Test the front speed sensor high signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 7 
7 Test the front speed sensor low signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 8 
8 Test the front speed sensor high signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
9 Test the front speed sensor low signal circuit for a short to the front speed sensor high signal circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
10 Replace the transfer case front propshaft speed sensor. Refer to Transfer Case Speed Sensor Replacement - Front .
Did you complete the repair?		 - Go to Step 12  -
11 Replace the transfer case shift control module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the repair?		 - Go to Step 12  -
12
  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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