Hummer H3. Manual — part 1648

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

-

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

DTC C0327

Circuit Description

The transfer case shift control module has four encoder channels, P, C, A and B, which are
supplied 5 volts each. The four encoder channels each run to a switch located inside the
encoder/motor assembly. When a particular encoder channel is active the switch is closed and 5
volts flows through the encoder signal return circuit. If the module wants to request motor
position a low side driver pulls the voltage low on the encoder signal return and the

Wiring Repairs .
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 .
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
Control Module References
for replacement, setup and
programming.
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 reset?

-

Go to Step 2 System OK

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3

corresponding channel circuit indicating motor position.

The transfer case shift control module supplies 5 volts on all encoder channels, thus as these
channels are pulled to ground, the module can interpret the location of the transfer case shift
position.

This DTC detects an open, high resistance or a short to voltage, in the encoder signal return
circuit or an open, high resistance or short to voltage in the encoder channel circuits.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0327 Encoder Circuit Malfunction

Conditions for Running the DTC

The ignition is ON.

The system voltage is 9-18 volts.

Conditions for Setting the DTC

The transfer case shift control module reads back a high voltage when a low voltage is expected
or low voltage when a high voltage is expected on the encoder channel circuits or the encoder
signal return circuit.

Action Taken When the DTC Sets

All motor activity will stop.

All the transfer case shift control switch mode indicators will be commanded OFF.

The SERVICE 4WD indicator will be latched on for the remainder of the current ignition
cycle.

If a new mode is requested while the DTC is present either current or history, the indicator
for the mode requested will flash for 15 seconds and then go out.

Conditions for Clearing the DTC

The transfer case shift control module will clear the DTC if the condition for setting the
DTC no longer exists.

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

History DTCs can be cleared using a scan tool.

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 determines if 2 or more of the 5 volts encoder signal circuits are shorted
together.

3: This step checks for proper voltage on the 4 encoder signal circuits.

4: This step tests for a short to voltage, open or high resistance on the encoder low reference
circuit.

5: This step determines which encoder signal circuits are shorted together.

6: This step determines if any of the encoder signal circuits have an open or high resistance
condition.

7: This step determines if a binding shift detent lever shaft is causing the DTC.

DTC C0327

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. Set the parking brake.

2. Raise the vehicle on a hoist.

Refer to Lifting and
Jacking the Vehicle in
General Information.

3. Disconnect the connector at

the transfer case.

4. Turn the ignition ON, with

the engine OFF.

5. Install a scan tool.

6. While monitoring the encoder

channels on the scan tool,
short to ground each of the
encoder channel circuits on

-

2007 Hummer H3

2007 TRANSMISSION Transfer Case - BW 4493/4494 - H3