Hummer H2. Manual - part 187

 

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Hummer H2. Manual - part 187

 

 

SYMPTOMS - BODY CONTROL SYSTEM 

Visual/Physical Inspection 

z

Inspect for aftermarket devices which could affect the operation of the body control system. Refer to 
Checking Aftermarket Accessories in Wiring Systems.  

z

Inspect the easily accessible or visible system components for obvious damage or conditions which could 
cause the symptom.  

Intermittent 

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for 
Intermittent Conditions and Poor Connections in Wiring Systems. 

Symptom List 

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: 

Power Mode Mismatch 

POWER MODE MISMATCH 

Circuit Description 

Normal vehicle class 2 communications and module operations will not begin until the system power mode has 
been identified. Discrete wires from the ignition switch contacts are monitored by the power mode master 
(PMM) module in order to determine the correct power mode. The PMM communicates the system power 
mode to all class 2 modules on the class 2 serial data line. Refer to Body Control System Description and 
Operation to identify which module is the PMM and the applicable power mode look up table.

3

Replace the control module setting the DTC as current. 
Refer to Control Module References .Did you 
complete the replacement?

Perform the programming or setup procedure for the 
module if required.

Go to 

Step 4

-

4

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

IMPORTANT: Review the system operation in order to familiarize yourself with the system 

functions. Refer to Body Control System Description and Operation .

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2

  

Test Description 

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

6: This step tests for battery voltage on the signal circuits that are not required.  

7: This step tests for no battery voltage on the required signal circuits.  

8: If any ignition switch parameters that should be inactive in the present ignition switch position are 
active, 2 ignition switch signal circuits may be shorted together.  

9: This step eliminates open circuits as the cause of the malfunction.  

Power Mode Mismatch 

Step

Action

Yes

No

Schematic Reference: Body Control System Schematics 
Connector End View Reference: Body Control System Connector End Views 
DEFINITION: This table is used if the observed vehicle power mode does not match the ignition switch 
position. 

IMPORTANT:

Open the driver door and leave it open during this test. This will disable the RAP power mode and 
eliminate this power mode from the power mode parameter list.

1

1. Install a scan tool.  

2. Turn OFF the ignition.  

3. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

Does the displayed power mode parameter match the actual 
ignition switch position?

Go to Step 2

Go to 

Step 6

2

1. Turn the ignition switch to the UNLOCK position.  

2. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

Does the displayed power mode parameter match the actual 
ignition switch position?

Go to Step 3

Go to 

Step 6

3

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

2. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

Does the displayed power mode parameter match the actual 
ignition switch position?

Go to Step 4

Go to 

Step 6

IMPORTANT:

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

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2

  

4

1. Turn the ignition switch to the CRANK position.  

2. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

Does the displayed power mode parameter match the actual 
ignition switch position?

Go to Step 5

Go to 

Step 6

5

1. Turn the ignition switch to the ACCY position.  

2. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

Does the displayed power mode parameter match the actual 
ignition switch position?

Go to Testing for 

Intermittent Conditions 

and Poor Connections in 

Wiring Systems

Go to 

Step 6

6

1. Turn OFF the ignition.  

2. Disconnect the PMM.  

3. Hold the ignition switch in the position that indicated 

the incorrect power mode.  

4. With a test lamp attached to a good ground, test the 

PMM ignition switch inputs for voltage. Refer to Body 
Control System Description and Operation .  

Is voltage present on only the inputs specified for the ignition 
switch position?

IMPORTANT:

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

Go to Step 7

Go to 

Step 8

7

1. Hold the ignition switch in the position that indicated 

the incorrect power mode.  

2. With a test lamp attached to a good ground, test the 

PMM ignition switch inputs for voltage. Refer to Body 
Control System Description and Operation .  

Is voltage not present on any inputs specified for the ignition 
switch position?

IMPORTANT:

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

Go to Step 9

Go to 

Step 

11

8

1. Disconnect the ignition switch.  

2. Test the PMM ignition switch input circuits for a short 

to voltage. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems.  

3. Test the PMM ignition switch circuits for a short 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2

  

CONTROL MODULE REFERENCES 

between circuits. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems.  

Did you find and correct the condition?

Go to Step 14

Go to 

Step 

10

9

1. Disconnect the ignition switch.  

2. Test the PMM ignition switch input circuits for an 

open. Refer to Circuit Testing and Wiring Repairs in 
Wiring Systems.  

Did you find and correct the condition?

Go to Step 14

Go to 

Step 

10

10

Inspect for poor connections and terminal tension at the 
harness connector of the ignition switch. 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 14

Go to 

Step 

12

11

Inspect for poor connections and terminal tension at the 
harness connector of the PMM. 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 14

Go to 

Step 

13

12

Replace the ignition switch. Refer to Ignition Switch 
Replacement in Steering Wheel and Column. 
Did you complete the replacement?

Go to Step 14

-

13

Replace the PMM. Refer to Control Module 
References .Did you complete the replacement?

IMPORTANT:

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

Go to Step 14

-

14

1. Reconnect all disconnected components.  

2. With a scan tool, under the Diagnostic Circuit Check 

menu observe the Class 2 Power Mode parameter.  

3. Cycle the ignition switch through all possible positions 

one at a time.  

Does the displayed power mode parameter match the actual 
ignition switch position?

IMPORTANT:

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

System OK

Go to 

Step 1

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2

  

 

 

 

 

 

 

 

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