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Home >> Chevrolet >> 2004 >> Avalanche 2500 >> Repair and Diagnosis >> External Pages >> Different car >> Section 411 (Transfer Case - BW 4482-Nr4) >> Diagnostic Information and Procedures >> DTC C0306: Motor A or B Circuit >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Yukon XL and 2004 GMC Yukon. 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:  Tests motor A driver high for proper operation.
  2. 3:  Tests motor B driver high for proper operation.
  3. 4:  Tests motor A driver low for proper operation.
  4. 5:  Tests motor B driver low for proper operation.
  5. 6:  Tests motor control A and motor control B circuits for being shorted together.
  6. 7:  Tests motor control A for a short to ground, short to voltage, open, or high resistance.
  7. 8:  Tests motor control B for a short to ground, short to voltage, open, or high resistance.
DTC C0306

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 - Transfer Case? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Engage the parking brake.
  2. Turn the ignition OFF and raise the vehicle on a hoist.
  3. Disconnect the motor encoder connector at the transfer case.
  4. Turn the ignition ON.
  5. With a DMM, measure voltage by probing the motor control A circuit and take the other lead to a good ground.
  6. With a scan tool, command motor A driver high ON.
Does the DMM indicate battery voltage?		 - Go to Step 3  Go to Step 7 
3 
  1. With a DMM, measure voltage by probing the motor control B circuit and take the other lead to a good ground.
  2. With a scan tool, command motor B driver high ON.
Does the DMM indicate battery voltage?		 - Go to Step 4  Go to Step 8 
4 
  1. With a DMM, measure voltage by probing the motor control A circuit and take the other lead to ground.
  2. With a scan tool, command motor A driver low ON.
Does the voltage on the DMM match the voltage indicated?		 0 V Go to Step 5  Go to Step 7 
5 
  1. With a DMM, measure voltage by probing the motor control B circuit and use the other lead to probe one of the four encoder signal circuits.
  2. With a scan tool, command motor B driver low ON.
Does the DMM indicate voltage within the specified range?		 4.3-4.7 V Go to Step 6  Go to Step 8 
6  With a DMM, test motor control A and motor control B circuits for being shorted together.
Did you find and correct the condition?		 - Go to Step 11  Go to Step 9 
7  With a DMM, test the motor control A circuit 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 10 
8  With a DMM, test the motor control B circuit 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 10 
9 Replace the 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 .
Did you complete the repair?		 - Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.
Does the DTC set?		 - Go to Step 2  System OK
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