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