GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 Century 🢒 Body and Accessories 🢒 Lighting Systems 🢒 DTC B2533

Circuit Description

The fog lamp relay is energized by the fog lamp switch only when the Body Control Module (BCM) has activated the fog lamp enable circuit that supplies the fog lamp switch. The BCM will only activate the fog lamp enable circuit if the following conditions exist:

    • The ignition switch must be in the RUN position.
    • The headlamp switch must be in the Park or Headlamp ON position.
    • The headlamp dimmer switch must be in the LOW-BEAM position.

Conditions for Running the DTC

The BCM must be commanding the fog lamp relay to energize.

Conditions for Setting the DTC
    •  The fault code will set when the fog lamp enable circuit is active and a short to battery voltage is present.
    • The condition above must be present for more than 0.3 seconds.
    • If the short to battery voltage is on the output side of the fog lamp switch, the fault will only set when the fog lamp switch is in the ON position.

Action Taken When the DTC Sets

The BCM stores DTC B2533 in memory.

Conditions for Clearing the DTC
    • A current DTC B2533 will clear if the short to battery in the fog lamp enable circuit is no longer detected by the BCM.
    • A history DTC B2533 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • The BCM receives a clear code command from the scan tool.

Diagnostic Aids
    • If the DTC B2533 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring System.
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent short to battery in the fog lamp enable circuit.
       - The fog lamp relay coil is intermittently shorted to battery.
       - The BCM is intermittently shorted to battery.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Determines that the fault is current when the for lamp relay parameter does not change state.

  2. Verifies that there is a short to battery voltage in the fog lamp relay control circuit or related circuits. Not detecting a short to battery voltage would indicate that the fog lamp relay is internally shorted to battery voltage.

    3.

  3. Test for short to battery voltage internal to the BCM.

    4.

  4. Test for short to battery voltage on the fog lamps control circuit.

Step

Action

Yes

No

Schematic Reference: Fog Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Place the headlamp switch in the HEAD position
  4. Place the headlamp dimmer switch in the low beam position
  5. With a scan tool, observe the fog lamp relay parameter in the Body Control Module (BCM) data list.
  6. Turn the fog lamp switch ON and OFF.

Does the fog lamp relay parameter change state?

Go to Diagnostic Aids

Go to Step 3

3

  1. Disconnect the fog lamp relay.
  2. Turn the fog lamp switch ON.
  3. Using a test lamp connected to ground, probe the fog lamp relay control circuit at the underhood fuse block.

Does the test lamp illuminate?

Go to Step 4

Go to Step 9

4

  1. Disconnect the BCM.
  2. Using a test lamp connected to ground, probe the fog lamp relay control circuit at the underhood fuse block.

Does the test lamp illuminate?

Go to Step 5

Go to Step 11

5

  1. Disconnect the fog lamp switch.
  2. Using a test lamp connected to ground, probe the fog lamp relay control circuit at the underhood fuse block.

Does the test lamp illuminate?

Go to Step 7

Go to Step 6

6

Test the fog lamps enable circuit of the fog lamp switch for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 10

7

Test the control circuit of the fog lamp relay for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 8

8

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

Did you complete the replacement?

Go to Step 12

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9

Replace the fog lamp relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 12

--

10

Replace the fog lamp switch. Refer to Fog Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 12

--

11

Important: Perform the setup procedure for the Body Control Module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the Body Control Module (BCM). Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 12

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12
  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