GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) controls the fog lamp relay. The BCM gets an input from the fog lamp switch circuit and then energizes the fog lamp relay by grounding the fog lamp relay coil control circuit. The BCM grounds the fog lamp relay coil control circuit if the following conditions exist:

    • The ignition switch must be in the RUN position.
    • The headlamp switch must be in the PARK or HEAD position.
    • The headlamp dimmer switch must be in the LOW position.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2532 Front Fog Lamp Control Circuit Low

Conditions for Running the DTC

The BCM must not be commanding the fog lamp relay to energize.

Conditions for Setting the DTC

    • The BCM detects a short to ground or open in the fog lamp relay coil control circuit when the BCM is not trying to energize the fog lamp relay.
    • The condition above must be present for more than 0.3 seconds.

Action Taken When the DTC Sets

The BCM stores DTC B2532 in memory.

Conditions for Clearing the DTC

    • A current DTC B2532 will clear if the BCM no longer detects a short to ground or open in the fog lamp relay coil control circuit.
    • A history DTC B2532 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

Diagnostic Aids

    • If the DTC B2532 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent short to ground or open in fog lamp relay coil control circuit
       - The fog lamp relay coil is intermittently shorted to ground or open internally.
       - The BCM is intermittently shorted to ground or open internally.

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 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 fog lamp relay ON and OFF.

Does the fog lamp relay turn ON and OFF with each command?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the fog lamp relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side battery positive voltage supply circuit of the fog lamp relay with a test lamp that is connected to 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 fog lamp relay and the coil side battery positive voltage supply circuit of the fog lamp relay.
  2. With a scan tool, command the fog 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 fog lamp relay for a short to battery positive voltage or an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 9

7

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

Did you find and correct the condition?

Go to Step 14

Go to Step 9

8

Inspect for poor connections at the fog lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

9

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

10

Test for a open or high resistance in the coil side battery positive voltage supply circuit of the fog lamp relay. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

11

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

Did you complete the repairs?

Go to Step 14

--

12

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

Did you complete the replacement?

Go to Step 14

--

13

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 14

--

14

  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