Hummer H3. Manual — part 1124

TR Sw

The scan tool displays Park, Reverse, Neutral, Drive 5, Drive 4, Drive 3, Drive and Drive 1.
The scan tool displays the position of the transmission range switch.

DTC B1327

Circuit Description

The control modules on this vehicle monitor system voltage through the battery positive voltage
circuits. Damage to components and incorrect data can occur when the voltage is out of range.
This vehicle has multiple modules that will set this DTC. For more information on which modules
refer to Diagnostic Trouble Code (DTC) List - Vehicle

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1327 Device Power 1 Circuit Low

Conditions for Running the DTC

This DTC shall run only if the module has power, ground and the ignition is not in START mode.
This DTC shall execute regardless of the battery voltage.

Conditions for Setting the DTC

This DTC shall be set as current when the voltage falls below 9 volts for 1.2 seconds.

When the vehicle exits START, the module shall delay checking the voltage for 2 seconds.

Action Taken When the DTC Sets

A message shall be sent out to notify all other modules of low battery voltage.

The modules disable the setting of U codes and other DTCs.

Conditions for Clearing the DTC

The DTC will clear current status when the voltage is greater than 9.5 volts for 1.2 seconds.

A history DTC will clear after 50 consecutive ignition cycles, if the condition for the
malfunction is no longer present.

Use a scan tool.

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

DTC B1327

Step

Action

Values

Yes

No

Schematic Reference: Control Module References

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. Operate the vehicle within the

Conditions for Running DTC
B1327.

Does the scan tool indicate that DTC
B1327 is current in more than one
module?

-

Go to Step

6

Go to Step 3

3

1. Turn ON the ignition, with the

engine OFF.

2. With a scan tool, observe the

Battery Voltage Signal
parameter in the body control
module (BCM) data list.

Does the voltage measure greater
than the specified value?

9.4 V

Go to Step

11

Go to Step 4

4

1. Turn OFF the ignition.

2. Disconnect the BCM.

3. Turn ON the ignition, with the

engine OFF.

4. Measure the voltage between

the battery positive voltage
circuit of the BCM and the
ground circuit of the BCM.

Does the voltage measure greater
than the specified value?

9.4 V

Go to Step

5

Go to Battery
Inspection/Test
(Non-HP2)

5

Measure the voltage between the
battery positive voltage circuit of the
BCM and a good ground.

9.4 V

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

Does the voltage measure greater
than the specified value?

Go to Step

9

Go to Step 8

6

1. Turn OFF the ignition.

2. Disconnect the harness

connector of the module setting
the DTC B1327.

3. Measure the voltage between

the battery positive voltage
circuit of the module setting the
DTC B1327 and the ground
circuit of the module setting the
DTC B1327.

Does the voltage measure greater
than the specified value?

9.4 V

Go to Step

10

Go to Step 7

7

Measure the voltage between the
battery positive voltage circuit of the
BCM or module setting DTC B1327
and a good ground.
Does the voltage measure greater
than the specified value?

9.4 V

Go to Step

9

Go to Step 8

8

Test the battery positive voltage
circuit of the BCM or module setting
DTC B1327 for a high resistance or
an open. Refer to Circuit Testing
and Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

12

Go to Step 10

9

Test the ground circuit of the BCM
or module setting DTC B1327 for a
high resistance or an open. Refer to
Circuit Testing and Wiring
Repairs .
Did you find and correct the
condition?

-

Go to Step

12

Go to Step 10

Inspect for poor connections at the
harness connector of the BCM or
module setting DTC B1327. Refer to

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

DTC B1390

Circuit Description

The generator battery control module monitors the battery voltage for precision electrical power
management. The generator battery control module monitors both the battery sense positive
voltage circuit and the battery sense negative, ground, circuit to precisely determine system
voltage. If there is a difference between the less precise battery voltage, battery positive voltage
circuit and ground circuit and the more precise battery sense voltage of 1 volt or more for 10
seconds, then DTC B1390 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1390 Device Voltage Reference Input 1 Circuit

Conditions for Running the DTC

Vehicle in RUN mode and Engine Run Flag is False or True.

This diagnostic shall be run every 100 ms.

10

Testing for Intermittent
Conditions and Poor Connections
and Connector Repairs .
Did you find and correct the
condition?

-

Go to Step

12

Go to Step 11

11

Replace the affected module setting
DTC B1327. Refer to Control
Module References for
replacement, setup and
programming.
Did you complete the replacement?

-

Go to Step

12

-

12

1. Use the scan tool in order to

clear the DTCs.

2. Operate the vehicle within the

Conditions for Running the
DTC.

Does the DTC reset?

-

Go to Step

3

System OK

2007 Hummer H3

2007 ENGINE Engine Electrical - H3