Hummer H2. Manual - part 311

 

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Hummer H2. Manual - part 311

 

 

The park lamps will not operate or will remain always on.

Conditions for Clearing the MIL/DTC 

z

This DTC will clear on current status after the condition for setting the fault is corrected.  

z

A history DTC will clear after 100 consecutive ignition cycles without a fault present.  

z

History and current DTC(s) can be cleared using a scan tool.  

Test Description 

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

2: Listen for an audible click when the park lamp relay operates. Command both the ON and OFF states. 
Repeat the commands as necessary.  

3: Tests for voltage at the coil side of the park lamp relay.  

4: Verifies that the body control module (BCM) is providing ground to the park lamp relay.  

5: Tests if ground is constantly being applied to the park lamp relay.  

6: Tests if there is opposing voltage present or an open park lamp relay control circuit.  

12: After replacement of the BCM you must calibrate the new module for proper operation.  

DTC B2585 

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics 
Connector End View Reference: Lighting Systems Connector End Views or Body Control System 
Connector End Views in Body Control System

1

Did you perform the Lighting Systems 
Diagnostic System Check?

Go to Step 2

Go to Diagnostic 

System Check - 

Lighting Systems

2

1. Install a scan tool.  

2. Turn ON the ignition, with the engine 

OFF.  

3. With a scan tool, command the park lamp 

relay ON and OFF.  

Does the park lamp relay turn ON and OFF with 
each command?

Go to Testing for 

Intermittent Conditions 

and Poor Connections in 

Wiring Systems

Go to Step 3

3

1. Turn OFF the ignition.  

2. Disconnect the park lamp relay.  

3. Turn ON the ignition, with the engine 

OFF.  

4. Connect a test light between the battery 

positive voltage circuit of the parklamp 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

  

relay and a good ground.  

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

1. Connect a test lamp between the control 

circuit of the park lamp relay and the 
battery positive voltage circuit of the park 
lamp relay.  

2. With a scan tool, command the park lamp 

relay ON and OFF.  

Does the test lamp turn ON and OFF with each 
command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each 
command?

Go to Step 7

Go to Step 6

6

Test the control circuit of the park lamp relay 
for a short to voltage or an open. Refer to 
Circuit Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the control circuit of the park lamp relay 
for a short to ground. Refer to Circuit Testing 
and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Inspect for poor connections at the park lamp 
relay. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

Inspect for poor connections at the harness 
connector of the BCM. Refer to Circuit Testing
and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Repair the battery positive voltage circuit of the 
park lamp relay. Refer to Wiring Repairs in 
Wiring Systems. 
Did you complete the repair?

Go to Step 13

-

11

Replace the park lamp relay. Refer to Relay 
Replacement (Within an Electrical Center)
Relay Replacement (Attached to Wire 
Harness) in Wiring Systems. 
Did you complete the replacement?

Go to Step 13

-

12

Replace the body control module (BCM). Refer 
to Body Control Module Replacement in 

IMPORTANT:

Perform the setup procedure for the BCM.

-

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

  

DTC B2600 

Circuit Description 

The ambient light sensor is a light sensitive transistor that sends a variable voltage signal to the body control 
module (BCM) in response to the exterior light level. The BCM energizes the DRL relay by grounding the DRL 
relay control circuit. The DRL operate when the ambient light sensor indicates daytime, the ignition switch is in 
the RUN position and the gear selector is not in the park position. 

Conditions for Running the DTC 

The battery voltage must be between 9.0-16.0 volts. 

Conditions for Setting the DTC 

z

When the BCM sends a DRL OFF command and the DRL relay control circuit is shorted to ground.  

z

When the BCM sends a DRL ON command and the DRL relay control circuit is shorted to voltage or 
open.  

Action Taken When the DTC Sets 

The DRL will not operate or will remain always on. 

Conditions for Clearing the MIL/DTC 

z

This DTC will clear on current status after the condition for setting the fault is corrected.  

z

A history DTC will clear after 100 consecutive ignition cycles without a fault present.  

z

History and current DTCs can be cleared using a scan tool.  

Test Description 

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

2: Listen for an audible click when the DRL relay operates. Command both the ON and OFF states. 
Repeat the commands as necessary.  

Body Control System.Did you complete the 
replacement?

Go to Step 13

13

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 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

  

3: Tests for voltage at the coil side of the DRL relay.  

4: Verifies that the body control module (BCM) is providing ground to the DRL relay.  

5: Tests if ground is constantly being applied to the DRL relay.  

6: Tests if there is opposing voltage present or an open in the DRL relay control circuit.  

12: After replacement of the BCM you must calibrate the new module for proper operation.  

DTC B2600 

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics 
Connector End View Reference: Lighting Systems Connector End Views or Body Control System 
Connector End Views in Body Control System.

1

Did you perform the Lighting Systems Diagnostic 
System Check?

Go to Step 2

Go to Diagnostic 

System Check - 

Lighting Systems

2

1. Install a scan tool.  

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

3. With a scan tool, command the DRL relay 

ON and OFF.  

Does the DRL relay turn ON and OFF with each 
command?

Go to Testing for 

Intermittent Conditions 

and Poor Connections in 

Wiring Systems

Go to Step 3

3

1. Turn OFF the ignition.  

2. Disconnect the DRL relay.  

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

4. Connect a test lamp between the battery 

positive voltage circuit of the DRL relay 
and a good ground.  

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

1. Connect a test lamp between the control 

circuit and the battery positive voltage 
circuit of the DRL relay.  

2. With a scan tool, command the DRL relay 

ON and OFF.  

Does the test lamp turn ON and OFF with each 
command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each 
command?

Go to Step 7

Go to Step 6

6

Test the control circuit of the DRL relay for high 
resistance, an open, or a short to voltage. Refer to 
Circuit Testing and Wiring Repairs in Wiring 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

  

 

 

 

 

 

 

 

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