Hummer H3. Manual — part 1406

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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2585 Park Lamp Control Circuit

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

When the BCM receives a park lamp OFF command and the park lamp relay control circuit
is shorted to ground

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

Action Taken When the DTC Sets

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

Did you complete the replacement?

Go to Step 13

-

12

Replace the BCM. Refer to Control
Module References for replacement, setup
and programming.
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

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

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 park lamp relay operates. Command both the ON
and OFF states. Repeat the commands as necessary.

3: This step tests for voltage at the coil side of the park lamp relay.

4: This step verifies that the BCM is providing ground to the park lamp relay.

5: This step tests if ground is constantly being applied to the park lamp relay.

6: This step 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 Data
Communication Connector End Views

1

Did you perform the Diagnostic System
Check - Vehicle?

Go to Step 2

Go to

Diagnostic

System Check -

Vehicle

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

Go to Step 3

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

3

1. Turn OFF the ignition.

2. Disconnect the park lamp relay.

3. Turn ON the ignition, with the

engine OFF.

4. Probe the battery positive voltage

circuit of the park lamp relay with a
test lamp that is connected to 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 .
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 .
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 .
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 body control
module (BCM). Refer to Circuit Testing

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

DTC B2602 OR B2603

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B2602

Daytime Running Lamp Control Circuit Low or Open

DTC B2603

and Wiring Repairs .
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 .
Did you complete the repair?

Go to Step 13

-

11

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

Go to Step 13

-

12

Replace the BCM. Refer to Control
Module References for replacement,
setup and programming.
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

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3