Hummer H3. Manual — part 1652

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

2: This step tests the functionality of the mode switch.

3: This step tests the modules ability to operate the transfer case modes.

Transfer Case Shift Control Switch Inoperative

Step

Action

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. Install a scan tool.

2. Start the engine.

3. Place the transmission into Neutral.

4. Set the park brake.

5. Observe the Mode Switch Selected

parameter on the scan tool while
selecting each of the mode positions on
the switch.

Does the state change with the selection of
each of the mode positions?

Go to Step 5

Go to Step 3

3

Test the switch signal and 5-volt reference
circuits for an open, high resistance, short to
ground and short to voltage. Refer to Circuit
Testing and Wiring Repairs .
Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

Replace the mode selection switch. Refer to
Transfer Case Shift Control Switch
Replacement.
Did you complete the repair?

Go to Step 6

-

5

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 6

-

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

TRANSFER CASE SHIFT CONTROL SWITCH INDICATOR ALWAYS ON - TWO OR MORE

Circuit Description

The indicator lamps circuit consist of the following 5 individual lamps contained inside the
mode/range switch assembly:

4HI

4HI Lock

4LO Lock

Differential Lock

Neutral

The following lamps are contained inside the respective mode button for each lamp:

4HI

4HI Lock

4LO Lock

Differential Lock

When the ignition in ON, the transfer case shift control module illuminates the indicator that
corresponds to the current gear position by providing a ground through a current limiting driver.

The transfer case shift control module flashes each indicator lamp after a shift has been requested
and will continue to flash until the transfer case shift control module can complete the shift.

A solid state circuit located inside the switch supplies ignition voltage to the lamps. The solid
state circuit also receives voltage whenever the headlamp switch is in the parklamp or headlamp
position. When the solid state circuit receives voltage from the headlamp switch, the switch
reduces the voltage supplied to the indicator lamps, dimming the lamps when the headlamps are
ON.

6

1. Use the scan tool in order to clear the

DTCs.

2. Operate the vehicle in order to

determine if the symptom has been
corrected.

Is the symptom still present?

Go to Step 2

System OK

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

Test Description

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

2: This step tests the transfer case electrical control of the lamp circuits.

3: This step tests the suspect lamp circuits for a short to ground.

Transfer Case Shift Control Switch Indicator Always On - Two or More

Step

Action

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. Turn the ignition ON, with the engine

OFF.

2. Install a scan tool.

3. Use the scan tool in order to command

all the indicator lamps OFF.

Do all the lamps go OFF?

Go to Step 7

Go to Step 3

3

1. Use the scan tool in order to determine

the transfer case mode.

2. Use this information to determine which

lamp circuits are at fault.

3. Disconnect the mode switch.

4. Test the suspect lamp circuits for a short

to ground. Refer to Circuit Testing and
Wiring Repairs .

Is the suspect circuit shorted to ground?

Go to Step 4

Go to Step 6

4

1. Disconnect the transfer case shift control

module.

2. Test the suspect lamp circuits for a short

to ground. Refer to Circuit Testing and
Wiring Repairs .

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

TRANSFER CASE SHIFT CONTROL SWITCH INDICATOR FLASHES, THEN RETURNS TO
PREVIOUS MODE

Circuit Description

The transfer case shift control module flashes each indicator lamp after a shift has been requested
and continues to flash until the transfer case shift control module can complete the shift. If the
transfer case is unable to make a shift, the requested mode indicator flashes and returns to the
previous mode. If the requested mode indicator flashes for 15 seconds and returns to the previous
mode, this indicates the loss of a necessary input from another module. The transfer case shift
control module requires a vehicle speed sensor (VSS) signal, provided by the antilock brake
system (ABS) module and a PRNDL input provided by the transmission. These signals are
provided to the transfer case shift control module via class 2 and if not received the transfer case
will not shift.

If a new mode is requested and the requested mode indicator flashes less then 15 seconds and
returns to the previous mode, this indicates a transfer case fault. This symptom is caused by an
internal mechanical transfer case fault causing the shift detent lever shaft to bind or a fault within
the encoder motor.

Is the suspect circuit shorted to ground?

Go to Step 5

Go to Step 7

5

Repair short to ground in the suspect lamp
circuit. Refer to Circuit Testing and Wiring
Repairs .
Did you find and correct the condition?

Go to Step 8

-

6

Replace the mode switch. Refer to Transfer
Case Shift Control Switch Replacement.
Is the repair complete?

Go to Step 8

-

7

Replace the transfer case shift control module.
Refer to Control Module References for
replacement, setup and programming.
Is the repair complete?

Go to Step 8

-

8

1. Use the scan tool in order to clear the

DTCs.

2. Operate the vehicle in order to

determine if the symptom has been
corrected.

Is the symptom still present?

Go to Step 2

System OK

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3