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