GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Express - AWD 🢒 Restraints 🢒 SIR 🢒 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2580 Headlamp High Beam Control Circuit

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC
    • When the high beam headlamp relay control circuit is open or 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
    • 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.

  1. Listen for an audible click when the high beam relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. This step tests for voltage at the coil side of the high beam relay.

    3.

  3. This step verifies that the BCM is providing ground to the high beam relay.

    4.

  4. This step tests if ground is constantly being applied to the high beam relay.

    5.

  5. This step tests if there is opposing voltage present or an open high beam relay control circuit.

    6.

  6. After replacement of the BCM, you must calibrate the new module for proper operation.

Step

Action

Yes

No

Schematic Reference: Headlights Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the high beam relay ON and OFF.

Does the high beam 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 high beam relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test light between the battery positive voltage circuit of the headlamp high beam relay and 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 high beam relay and the battery positive voltage circuit of the high beam relay.
  2. With a scan tool, command the high beam 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 high beam relay for a short to battery positive 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 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

8

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

9

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

10

Repair the poor connection or an open in 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

--

11

Replace the high beam relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 13

--

12

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems 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