Hummer H2. Manual - part 2653

2

2. Start the engine.  

3. Set the Park brake.  

4. Place the transmission into 

neutral.  

5. With a scan tool, observe the 

4WD indicator modes in the tech 
2 transfer case data list.  

6. Select each of the modes.  

Does the scan tool indicate that the 
4WD indicators are in the correct state?

-

Go to Testing for 

Intermittent 

Conditions and Poor 

Connections in Wiring 

Systems

Go to Step 3

3

1. Disconnect and remove the mode 

switch.  

2. Connect a DMM between the 

switch signal and 5 volt reference 
pins on the switch.  

3. Measure the resistance through 

the mode switch while pressing 
and holding each of the mode 
buttons and comparing values.  

Does the DMM indicate all resistance 
values within the specified ranges?

4 HI 1.50-

1.53K ohm 

4 HI Lock 

656.2-669.4 

ohm 

4 LO Lock 

2.32-2.36K 

ohm 

Differential 

Lock 63.8-

65.8 ohm 

Normal 9-

9.18K ohm 

Neutral 1.010-

1.031K ohm

Go to Step 4

Go to Step 7

4

Check the voltage on the 5 volt 
reference circuit. 
Was the voltage within the specified 
range?

4.8-5.1 V

Go to Step 6

Go to Step 5

5

Test the 5 volt reference circuit for an 
open, short to ground, short to voltage, 
or high resistance. Refer to Circuit 
Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

-

Go to Step 9

Go to Step 8

6

Test the switch signal circuit for a short 
to voltage, short to ground, open, or 
high resistance. Refer to Circuit 
Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

-

Go to Step 9

Go to Step 8

7

Replace the mode switch. Refer to 
Transfer Case Shift Control Switch 
Replacement . 

-

-

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

DTC C0306 

Circuit Description 

The transfer case motor is a bi-directional, permanent magnet, D.C. motor. When energized, through motor 
control A or motor control B, the ground is provided by the opposing motor control circuit and then grounded 
through the transfer case shift control module ground circuit, the motor, through a series of gears, rotates a shaft 
which moves the mode and range forks to shift the transfer case between the following ranges: 

z

4HI  

z

4HI Lock  

z

4LO Lock  

z

N  

This DTC detects an open, short to voltage, or short to ground in the motor control A or motor control B 
circuits, or an open, or short to ground inside the motor. 

Conditions for Running the DTC 

z

The ignition is ON.  

z

The system voltage is 9-18 volts.  

Conditions for Setting the DTC 

z

The system will test the motor circuits by testing for unwanted voltage.  

z

Then, the system supplies voltage on each of the motor circuits and reads the voltage back on the other 
circuit.  

z

If the system detects a problem with the circuits, the DTC is logged. The transfer case shift control 
module senses a low voltage return in the motor control A or motor control B circuits when a high 
voltage is expected.  

z

The fault must remain current for 1.2 seconds to set the DTC. 

Did you complete the repair?

Go to Step 9

8

Replace the transfer case shift control 
module. Refer to Transfer Case Shift 
Control Module Replacement 
Did you complete the repair?

-

Go to Step 9

-

9

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 reset?

-

Go to Step 2

System OK

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

Action Taken When the DTC Sets 

z

All shifting will be disabled.  

z

The SERVICE 4WD indicator will remain illuminated for the remainder of the current ignition cycle.  

Conditions for Clearing the DTC 

z

The transfer case shift control module will clear the DTC if the condition for setting the DTC is not 
currently present.  

z

A history DTC will clear after 33 consecutive ignition cycles without a fault present.  

z

History DTCs can be cleared using a scan tool.  

Test Description 

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

2: This step tests motor A driver high for proper operation.  

3: This step tests motor B driver high for proper operation.  

4: This step tests motor A driver low for proper operation.  

5: This step tests motor B driver low for proper operation.  

6: This step tests motor control A and motor control B circuits for being shorted together.  

7: This step tests motor control A for a short to ground, short to voltage, open, or high resistance.  

8: This step tests motor control B for a short to ground, short to voltage, open, or high resistance.  

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

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 

-

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

ON.  

Does the digital multimeter (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, check 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, check 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, check 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 
Motor/Encoder 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

-

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2