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