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Test Description

WARNING: This page is about a different car, the 2004 Oldsmobile Bravada and 2004 Buick Rainier. 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 the battery positive and ground circuits for poor connections.
  2. 3:  This step tests the encoder motor for an internal short to ground.
  3. 4:  This step helps isolate motor malfunctions from the transfer case shift control module and wiring.
  4. 5:  This step tests for an open, high resistance, short to ground or short to voltage.
DTC C0306

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  Check the battery positive and ground circuits for poor connections. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 3 
3 
  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 6  Go to Step 4 
4 
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 5  Go to Step 6 
5  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 8  Go to Step 7 
6 Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement  .
Did you complete the repair?		 - Go to Step 8  -
7
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 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 8  -
8
  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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