Hummer H2. Manual - part 1146

go to step 14 . If no, go to step 10 .  

9. Disconnect the ignition switch. Test the PMM ignition switch input circuits for an open. Did you find and 

correct the condition? If yes, go to step 14 . If no, go to next step.  

10. Inspect for poor connections and terminal tension at the harness connector of the ignition switch. Did you 

find and correct the condition? If yes, go to step 14 . If no, go to step 12 .  

11. Inspect for poor connections and terminal tension at the harness connector of the PMM. Did you find and 

correct the condition? If yes, go to step 14 . If no, go to step 13 .  

12. Replace the ignition switch. After repairs, go to step 14 .  

13.  

Replace the PMM. After replacement, go to next step.  

14.  

Reconnect all disconnected components. With a scan tool, under the Diagnostic Circuit Check menu 
observe the Class 2 Power Mode parameter. Cycle the ignition switch through all possible positions one 
at a time. Does the displayed power mode parameter match the actual ignition switch position? If yes, 
system OK. If no, go to step 1 .  

SCAN TOOL DATA LIST 

Scan Tool Data List 

SCAN TOOL DATA DEFINITIONS 

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. 

NOTE:

After replacement of the PMM perform the programming or set up 
procedure if required. 

NOTE:

The engine may start during this procedure. Turn the ignition OFF after 
verifying all power modes. 

Scan Tool Parameter 

Data List 

Units 

Displayed 

Typical Data 

Value 

Ignition On, With Engine Off 

Ignition 1 Signal 

Engine 1,2 

Data 

Volts 

9-14 volts 

GEN L-Terminal Signal 
Command 

Engine 2 Data  OK/No Output 

OK 

GEN F-Terminal Signal 

Engine 2 Data 

% 

10-90% 

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

DIAGNOSTIC TROUBLE CODE LIST 

Diagnostic Trouble Code List 

DIAGNOSTIC TESTS 

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 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 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 DTC Sets 

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 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.  

DTC 

Module(s) 

B1327 

BCM 

B1328 

BCM 

P0562 

PCM 

P0563 

PCM 

P0615 

PCM 

P1637 

PCM 

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

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.  

Diagnostic Procedures 

1. Did you perform the Engine Electrical Diagnostic System Check? If yes, go to next step. If no, go to 

DIAGNOSTIC SYSTEM CHECK - ENGINE ELECTRICAL .  

2. Install a scan tool. Turn ON the ignition, with the engine OFF. 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. If 
yes, go to step 6 . If no, go to next step.  

3. Turn OFF the ignition. Disconnect the harness connector of the module setting the DTC B1327. 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. If yes, go to step 6 . If no, go to next step.  

4. Test the batter positive voltage circuit of the module setting the code for a high resistance or an open. Did 

you find and correct the condition? If yes, go to step 8 . If no, go to next step.  

5. Test the ground sense circuit of the module setting the code for a high resistance or an open. Did you find 

and correct the condition? If yes, go to step 8 . If no, go to next step.  

6. Inspect for poor connections at the harness connector of the module setting the DTC. Did you find and 

correct the condition? If yes, go to step 8 . If no, go to next step.  

7.  

Replace the module setting the DTC. Refer to Body Control Module. After replacement, go to next step.  

8. Use the scan tool in order to clear the DTCs. Operate the vehicle within the CONDITIONS FOR 

RUNNING DTC . Does the DTC reset? If yes, go to step 2 . If no, system OK.  

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 DTC 

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

NOTE:

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

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

shall execute regardless of the battery voltage, except when the DTC B1390 is set current.  

Conditions For Setting 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 
set current in the affected module.  

Action Taken When 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 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 jump start 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.  

Diagnostic Procedures 

1. Did you perform the Engine Electrical Diagnostic System Check? If yes, go to next step. If no, go to 

DIAGNOSTIC SYSTEM CHECK - ENGINE ELECTRICAL .  

2. Install a scan tool. Turn ON the ignition, with the engine OFF. 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? If yes, go to step 4 . If no, go to next step.  

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? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .  

4.  

Replace the module setting the code. Refer to Body Control Module. After replacement, go to next step. 

NOTE:

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

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2