Hummer H2. Manual - part 1911

3. Test the ignition feed circuit to the PCM for high resistance or open. Did you find and correct the 

condition? If yes, go to step 7 . If no, go to step 5 .  

4. Inspect for poor connections at the PCM. If you find a poor connection, repair the condition as necessary. 

Did you find and correct the condition? If yes, go to step 7 . If no, go to step 6 .  

5. Repair the ignition feed circuit to the PCM for an open or a short to ground. After repairs, go to step 7 .  

6.  

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement. After repairs, go to next 
step.  

7. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan 

tool. Operate the vehicle within the CONDITIONS FOR RUNNING DTC . Does the DTC reset? If yes, 
go to step 2 . If no, system OK.  

DTC P0563 

Circuit Description 

The powertrain control module (PCM) continuously monitors that the system voltage stays within the proper 
range. If the PCM detects an excessively high system voltage, DTC P0563 will set. A high voltage condition 
may cause a stalling condition or other driveability concerns.  

Conditions For Running DTC 

z

The engine run time is more than 20 seconds.  

z

Engine running above 1200 RPM.  

z

Vehicle speed above 8 km/h (5 mph).  

Conditions For Setting DTC 

z

The PCM senses the system voltage is above 19 volts.  

z

All of the conditions are present for 5 seconds.  

Action Taken When DTC Sets 

z

The PCM stores DTC P0563 in the PCM memory when the diagnostic runs and fails.  

z

The PCM will record the operating conditions at the time the diagnostic fails. The PCM stores this 
information in Failure Records.  

z

The PCM disables most outputs.  

z

The transmission defaults to a predetermined gear.  

z

The torque converter clutch (TCC) operation is inhibited.  

z

The instrument panel cluster (IPC) displays a message.  

z

The malfunction indicator lamp (MIL) will not illuminate. 

NOTE:

The replacement PCM must be programmed. 

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

Conditions For Clearing DTC 

z

The Conditions for Setting the DTC are no longer present.  

z

A history DTC will clear after 40 malfunction free ignition cycles.  

z

The Powertrain Control Module (PCM) receives the clear code command from the scan tool.  

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. Turn OFF all the accessories. Measure the battery voltage at the battery using the DMM. Operate the 

engine speed above 2000 RPM. Is the battery voltage less than 19 V? If yes, go to step 4 . If no, go to 
next step.  

3. Replace the generator. Refer to GENERATOR . After replacement, go to step 5 .  

4.  

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement. After replacement, go to 
next step.  

5. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan 

tool. Operate the vehicle within the CONDITIONS FOR RUNNING DTC . Does the DTC reset? If yes, 
go to step 2 . If no, system OK.  

DTC P0615 

Circuit Description 

The PCM uses Output Driver Modules (ODMs) to control many functions of the engine. The ODMs supply the 
ground path for the PCM controlled device when the PCM commands the device ON. Each ODM is able to 
control several outputs. The PCM monitors the ODMs for circuit conditions that are incorrect for the 
commanded state of the ODM. If the PCM detects an improper circuit condition in the ODM that controls the 
starter relay, DTC P0615 will set.  

Conditions For Running DTC 

System voltage is between 8-16 volts.  

Conditions For Setting DTC 

z

The PCM detects an improper voltage level on the output circuit that controls the starter relay.  

z

The condition exists for at least 2 seconds.  

Action Taken When DTC Sets 

z

The PCM will not illuminate the Malfunction Indicator Lamp (MIL). 

NOTE:

The replacement PCM must be programmed. 

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

z

The PCM will store the conditions present when the DTC set as Fail Records data only.  

Conditions For Clearing DTC 

z

The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.  

z

The DTC can be cleared by using the scan tool Clear DTC Information function.  

Diagnostic Aids 

Ignition system DTCs set with the ignition switch in the START position if the starter relay or the starter is 
inoperative. When the PCM enables starter operation, the PCM also initiates the diagnostic test routines for 
DTC P0335. If a condition exists which prevents the engine from cranking, the PCM will not receive signal 
input from the CKP and CMP sensors, and the DTCs will set.  

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the 
condition. The information may help determine how often the condition that set the DTC occurs.  

Test Description 

The number(s) below refer to the step number(s) on the diagnostic table.  

2 - Listen for an audible click when the Start 1 relay operates. Turn the ignition switch back and forth 
from the ON to START positions. Repeat this as necessary.  

3 - Tests for voltage at the coil side of the Start 1 relay. The PCM IGN fuse supplies power to the coil 
side of the Start 1 relay.  

4 - Verifies that the PCM is providing ground to the Start 1 relay.  

5 - Tests if ground is constantly being applied to the Start 1 relay.  

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. Turn the ignition back and forth from the 

ON to START positions. Does the Start 1 relay turn ON and OFF with each command? If yes, problem is 
intermittent. If no, go to next step.  

3. Turn OFF the ignition. Disconnect the Start 1 relay. Turn ON the ignition, with the engine OFF. Probe 

the battery positive voltage of the Start 1 relay coil circuit with a test lamp that is connected to a good 
ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step 8 .  

4. Connect a test lamp between the control circuit of the Start 1 relay and the battery positive voltage of the 

Start 1 relay coil circuit. Turn the ignition back and forth from the ON to START positions. Does the test 
lamp turn ON and OFF with each command? If yes, go to step 6 . If no, go to next step.  

5. Test the control circuit of the Start 1 relay for a short to voltage or an open. Did you find and correct the 

condition? If yes, go to step 11 . If no, go to step 7 .  

6. Inspect for poor connections at the Start 1 relay. Did you find and correct the condition? If yes, go to step 

11 . If no, go to step 9 .  

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2

  

7. Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step 11 . If 

no, go to step 10 .  

8. Repair the battery positive voltage circuit of the Start 1 relay. After repairs, go to step 11 .  

9. Replace the Start 1 relay. Did you complete the replacement? After replacement, go to step 11 .  

10.  

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement. After replacement, go to 
next step.  

11. Review and record the scan tool Fail Records data. Use the scan tool in order to clear the DTC. Operate 

the vehicle within the CONDITIONS FOR RUNNING DTC . Using the scan tool, observe the Specific 
DTC Information for DTC P0615 until the test runs. Does the scan tool indicate that DTC P0615 failed 
this ignition? If yes, go to step 2 . If no, system OK.  

DTC P1637 

Circuit Description 

The powertrain control module (PCM) uses the generator turn on signal circuit to control the generator. A high 
side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is 
desired, the PCM sends a 10-11 volt signal to the voltage regulator via the generator turn on signal circuit. This 
causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the 
PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating 
conditions, the PCM can turn Off the generator by turning Off the 10-11 volt signal on the generator turn on 
signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn on signal 
circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage 
regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the 
generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.  

Conditions For Running DTC 

z

The ignition is ON.  

z

System voltage between 9.0-18.0 volts.  

Conditions For Setting DTC 

z

An improper voltage level has been detected on the generator L-terminal circuit.  

z

The conditions are present for at least 30 seconds.  

Action Taken When DTC Sets 

The PCM stores conditions which were present when the DTC set as Failure Records only. This information 
will not be stored as Freeze Frame Records.  

Conditions For Clearing DTC 

NOTE:

The replacement PCM must be programmed. 

 

2004 Hummer H2 

2004 STARTING & CHARGING SYSTEMS Starters - H2