GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Accessories 🢒 Navigation Systems 🢒 DTC B2580

Circuit Description

When the turn signal/multifunction switch is placed in the headlamps high or flash to pass (FTP) position, ground is applied to the body control module (BCM) through the headlamp high beam signal circuit or the flash to pass switch signal circuit. The BCM then applies ground to the headlamp high beam relay control circuit which energizes the high beam relay, applying battery voltage to the high beam headlamps.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2580 Headlamp High Beam Control Circuit

DTC Symptom

DTC Symptom Descriptor

01

Short to Voltage

06

Open or Short to Ground

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC
    • DTC B2580 01 will set when the BCM detects a short to battery voltage in the headlamp high beam relay control circuit.
    • DTC B2580 06 will set when the BCM detects an open or short to ground in the headlamp high beam relay control circuit.

Action Taken When the DTC Sets
    • When DTC B2580 01 is present, the high beam headlamps will not operate.
    • When DTC B2580 06 is present, the high beam headlamps will remain ON.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • You issue a scan tool CLEAR DTCs command.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference: Master Electrical Component List

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.

Is DTC 2580 01 present?

Go to Step 3

Go to Step 5

3
  1. Remove the high beam relay from the underhood fuse block.
  2. Connect a test lamp between the headlamp high beam relay control circuit and ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 14

4

Locate and repair a short to battery voltage in the headlamp high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 13

5

Are the high beam headlamps always ON?

Go to Step 6

Go to Step 9

6
  1. Turn OFF the ignition.
  2. Disconnect the body control module (BCM) C1 harness connector.
  3. Turn ON the ignition, with the engine OFF.

Do the high beam headlamps turn OFF?

Go to Step 12

Go to Step 7

7

Locate and repair a short to ground in the headlamp high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 8

8

Remove the high beam relay from the underhood fuse block.

Do the high beam headlamps turn OFF?

Go to Step 14

Go to Step 13

9
  1. Turn OFF the ignition.
  2. Remove the high beam relay from the underhood fuse block.
  3. Connect a test lamp between the high beam relay battery voltage supply circuit and the headlamp high beam relay control circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. Place the turn signal/multifunction switch in the high beam position.

Does the test lamp illuminate?

Go to Step 14

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Disconnect the underhood fuse block C3 harness connector.
  3. Connect a test lamp between battery voltage and the headlamp high beam relay control circuit at the underhood fuse block C3 harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Place the turn signal/multifunction switch in the high beam position.

Does the test lamp illuminate?

Go to Step 13

Go to Step 11

11

Locate and repair an open or high resistance in the headlamp high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 12

12

Inspect for poor connections at the C1 harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 15

13

Inspect for poor connections at the C3 harness connector of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 16

14

Replace the high beam relay. Refer to Relay Replacement .

Did you complete the repair?

Go to Step 17

--

15

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

Did you complete the replacement?

Go to Step 17

--

16

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement .

Did you complete the repairs?

Go to Step 17

--

17
  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