Hummer H2. Manual — part 1158

Ignition 1 Signal

The scan tool displays the current voltage at the battery.

GEN L-Terminal Signal Command

The scan tool displays OK/No Output. The scan tool displays OK until malfunction is detected on the
generator L terminal circuit, then it reads No Output.

GEN F-Terminal Signal

The scan tool displays 0%-100%. The scan tool displays 0%-5% until the engine is running, then the
percentage value varies depending on electrical loads.

DIAGNOSTIC TROUBLE CODE (DTC) LIST

Diagnostic Trouble Code (DTC) List

DTC B1327

Circuit Description

All vehicle modules monitor system voltage. The system voltage message is sent to other modules via Class 2
message. When the system voltage drops below the specified range DTC B1327 shall set within the affected
module.

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, except when the DTC B1390 is set current.

Conditions for Setting the DTC

z

This DTC shall be set as current when the voltage falls below 9.0 volts for 1.2 seconds.

z

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

Action Taken When the DTC Sets

DTC

Diagnostic Procedure

Modules

B1327

DTC B1327

BCM

B1328

DTC B1328

BCM

P0562

DTC P0562

PCM

P0563

DTC P0563

PCM

P1637

DTC P1637

PCM

P0622

DTC P0622

PCM

P0615

DTC P0615

PCM

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2

z

A message shall be sent out on the class 2 lines to notify all other modules of low battery voltage.

z

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

Conditions for Clearing the DTC

z

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

z

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

z

Use the ON-Board clearing DTCs feature.

z

Use a scan tool.

Test Description

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

3: Tests for the proper voltage at battery positive voltage sense circuit of the module, if voltage is not
within the proper operating range, the voltage sense circuit needs to be tested.

4: Tests the circuit for high resistance.

5: Tests for the proper ground circuit for the module.

DTC B1327

Step

Action

Value

(s)

Yes

No

Schematic Reference:Starting and Charging Schematics or Power Distribution Schematics in
Wiring Systems
Connector End View Reference:Master Electrical Component List in Wiring Systems

1

Did you perform the Engine Electrical Diagnostic System
Check?

-

Go to

Step 2

Go to Diagnostic

System Check -

Engine Electrical

2

1. Install a scan tool.

2. Turn ON the ignition, with the engine OFF.

3. With a scan tool, observe the battery voltage parameter

in the affected module data list. Or with a DMM,
measure the battery voltage at the appropriate circuit of
the module.

Does the voltage measure greater than the specified value?

9.4 V

Go to

Step 6

Go to Step 3

3

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

9.4 V

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2

DTC B1328

Circuit Description

All vehicle modules monitor system voltage. The system voltage message is sent to other modules via Class 2
message. When the system voltage is above the specified range DTC B1328 shall set within the affected
module.

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, except when the DTC B1390 is set current.

Conditions for Setting the DTC

This DTC will set as current when the voltage is greater than 15.9 volts for 1.2 seconds and DTC B1390 is not

B1327.

Does the voltage measure greater than the specified value?

Go to

Step 6

Go to Step 4

4

Test the batter positive voltage circuit of the module setting
the code for a high resistance or an open. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to

Step 8

Go to Step 5

5

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

-

Go to

Step 8

Go to Step 6

6

Inspect for poor connections at the harness connector of the
module setting the DTC. Refer to Testing for Intermittent
Conditions and Poor Connections and Connector Repairs
in Wiring Systems.
Did you find and correct the condition?

-

Go to

Step 8

Go to Step 7

7

Replace the module setting the DTC. Refer to Control
Module References in Body Control System.Did you
complete the replacement?

IMPORTANT:

Perform the setup procedure for the module setting the
code, if necessary.

-

Go to

Step 8

-

8

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 ELECTRICAL Engine Electrical - Hummer H2

set current in the affected module.

Action Taken When the DTC Sets

z

A message shall be sent out on the class 2 lines to notify all other modules of high than normal battery
voltage.

z

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

Conditions for Clearing the DTC

z

The DTC will clear current status when the voltage is less than 15.5 volts for 1.2 seconds.

z

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

z

Use a scan tool.

Diagnostic Aids

Using a battery charger to jumpstart the vehicle may set DTC B1328 as a history code.

Test Description

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

3: Tests for the proper voltage at the affected module. If the voltage is not within the proper operating
range, the charging system needs to be checked.

4: Setup procedure for the module replacement.

DTC B1328

Step

Action

Yes

No

1

Did you perform the Engine Electrical Diagnostic System
Check?

Go to

Step 2

Go to Diagnostic System

Check - Engine Electrical

2

1. Install a scan tool.

2. Turn ON the ignition, with the engine OFF.

3. With a scan tool, monitor the DTC Information for DTC

B1328 in the affected module.

Does the scan tool indicate that DTC B1328 is current?

Go to

Step 4

Go to Step 3

3

With a scan tool, monitor the DTC Information for DTC
B1328 in the affected module.
Does the scan tool indicate that DTC B1328 is current?

Go to

Step 4

Go to Diagnostic Aids

4

IMPORTANT:

Perform the setup procedure for the module setting the
code, if necessary.

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2