Hummer H2. Manual - part 310

DTC B2580

Circuit Description

When the body control module (BCM) receives a ground signal from the multifunction high beam or flash to
pass (FTP) switch commanding to illuminate the high beam headlamps, the BCM will energize the high beam
relay by grounding the high beam relay control circuit.

Conditions for Running the DTC

The battery voltage must be between 9.0-16.0 volts.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

Inspect for poor connections at the headlamp low
beam 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

Inspect for poor connections at the harness
connector of the body control module (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

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

Go to Step 13

Replace the headlamp low beam 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

Replace the BCM. Refer to Body Control
Module Replacement in Body Control
System.Did you complete the replacement?

IMPORTANT:

Perform the setup procedure for the BCM.

Go to Step 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

Conditions for Setting the DTC

When the BCM receives a high beam headlamp OFF command and the high beam headlamp relay control
circuit is shorted to ground.

When the BCM receives a high beam headlamp ON command and the high beam headlamp relay control
circuit is shorted to voltage or open.

When the high beam relay coil side is open or the battery positive voltage to the high beam relay is open.

Action Taken When the DTC Sets

The high beam headlamps will not operate or will remain always on.

Conditions for Clearing the MIL/DTC

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

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

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 high beam relay operates. Command both the ON and OFF states.
Repeat the commands as necessary.

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

4: Verifies that the BCM is providing ground to the high beam relay.

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

6: Tests if there is opposing voltage present or an open high beam relay control circuit, including the
relay coil side.

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

DTC B2580

Step

Action

Yes

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

Did you perform the Lighting Systems
Diagnostic System Check?

Go to Step 2

Go to Diagnostic

System Check -

Lighting Systems

1. Turn ON the ignition, with the engine

OFF.

2. Place the headlamp switch in the ON

position.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

3. Place the headlamp dimmer switch in the

high beam position.

4. Place the headlamp switch in the OFF

position.

Does the high beam headlamps operate as
expected?

Go to Testing for

Intermittent Conditions

and Poor Connections in

Wiring Systems

Go to Step 3

1. Turn OFF the ignition.

2. Disconnect the high beam relay.

3. Turn ON the ignition, with the engine

OFF.

4. Connect a test lamp between the control

circuit of the headlamp high beam relay
and a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

1. Connect a test lamp between the control

circuit of the high beam relay and the
battery positive voltage circuit of the high
beam relay.

2. While observing the test lamp, place the

headlamp switch in the ON position, and
then the OFF position.

Does the test lamp turn ON and OFF with each
cycle of the switch?

Go to Step 8

Go to Step 5

Does the test lamp remain illuminated with each
cycle of the switch?

Go to Step 7

Go to Step 6

Test the control circuit of the high beam 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

Test the control circuit of the high beam 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

Inspect for poor connections at the high beam
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

Inspect for poor connections at the harness
connector of the body control module (BCM).
Refer to Circuit Testing and Wiring Repairs

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

DTC B2585

Circuit Description

When the body control module (BCM) receives a ground signal from the headlamp switch commanding to
illuminate the park lamps, the BCM will energize the park lamp relay by grounding the park lamp relay control
circuit.

Conditions for Running the DTC

The battery voltage must be between 9.0-16.0 volts.

Conditions for Setting the DTC

When the park lamp relay control circuit is open or shorted to ground.

When the BCM receives a park lamp ON command and the park lamp relay control circuit is shorted to
voltage.

When the park lamp relay coil side is open or the battery positive voltage to the low beam relay is open.

Action Taken When the DTC Sets

in Wiring Systems.
Did you find and correct the condition?

Go to Step 13

Go to Step 12

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

Go to Step 13

Replace the high beam 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

Replace the BCM. Refer to Body Control
Module Replacement in Body Control
System.Did you complete the replacement?

IMPORTANT:

Perform the setup procedure for the BCM.

Go to Step 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

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