GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying battery voltage to the front fog lamp relay control circuit. When the front fog lamp relay is energized, battery voltage is applied via the FOG LAMP fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2530 Front Fog Lamps Control Circuit

DTC Symptom

DTC Symptom Descriptor

02

Short to Ground

05

Open or Short to Voltage

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

    • DTC B2530 02 will set when the BCM detects a short to ground in the front fog lamp relay control circuit.
    • DTC B2530 05 will set when the BCM detects an open or short to voltage in the front fog lamp relay control circuit.

Action Taken When the DTC Sets

    • When DTC B2530 02 is present, the front fog lamps will not operate when the park lamps are ON and the front fog lamp switch is active.
    • When DTC B2530 05 is present, the front fog lamps and/or the front fog lamp indicator will be ON at all times or will not operate.

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: Fog Lights 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 B2530 02 present?

Go to Step 3

Go to Step 5

3

  1. Turn OFF the ignition.
  2. Disconnect the underhood fuse block C3 harness connector.
  3. Connect a test lamp between the front fog lamp relay control circuit and ground.
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the park lamps.
  6. Turn ON the front fog lamps.

Does the test lamp illuminate?

Go to Step 7

Go to Step 4

4

Locate and repair a short to ground in the front fog lamp relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 12

5

  1. Turn OFF the ignition.
  2. Disconnect the body control module (BCM) C1 harness connector.
  3. Connect a test lamp between the front fog lamp relay control circuit and ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 11

6

Locate and repair a short to battery voltage in the front fog lamp relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 8

7

  1. Remove the front fog lamp relay.
  2. Using a test lamp connected to battery voltage, probe the front fog lamp relay control circuit at the underhood electrical center.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

8

  1. Remove the front fog lamp relay.
  2. Disconnect the underhood fuse block C3 harness connector.
  3. Using a test lamp connected to ground, probe the front fog lamp relay control circuit at the underhood fuse block.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

9

Replace the front fog lamp relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 14

--

10

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

Did you complete the replacement?

Go to Step 14

--

11

Locate and repair an open in the front fog lamp relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

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 14

Go to Step 13

13

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

Did you complete the replacement?

Go to Step 14

--

14

  1. Use a 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