Hummer H3. Manual — part 1647

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?

Neutral

2,424-2,574

ohms

4 HI 3,553-

3,773 ohms

4 HI Lock

1,817-1,930

ohms

4 LO Lock

5,256-5,581

ohms

Differential

Lock 747-

793 ohms

Normal

16,878-

17,922 ohms 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 .
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 .
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.
Did you complete the repair?

-

Go to Step 9

-

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

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:

4HI

4HI Lock

4LO Lock

Neutral

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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0306 Motor A or B Circuit Malfunction

Conditions for Running the DTC

8

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 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

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

The ignition is ON.

The system voltage is 9-18 volts.

Conditions for Setting the DTC

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

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

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.

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

Action Taken When the DTC Sets

All shifting will be disabled.

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

Conditions for Clearing the DTC

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

A history DTC will clear after 100 consecutive ignition cycles without a fault present.

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.

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

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 - Vehicle?

-

Go to Step 2

Go to
Diagnostic
System
Check -
Vehicle

2

1. Engage the parking brake.

2. Turn the ignition OFF and

raise the vehicle on a hoist.
Refer to Lifting and
Jacking the Vehicle .

3. Disconnect the motor

encoder connector at the
transfer case.

4. Turn the ignition ON.

5. With a digital multimeter

(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

-

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3