GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 Regal 🢒 DTC 🢒 DTC B2588

Circuit Description

The Body Control Module (BCM) controls the park lamp relay through the park lamp relay control circuit. The BCM grounds the park lamp relay control circuit which energizes the park lamp relay.

Conditions for Running the DTC

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

Conditions for Setting the DTC
    • The BCM detects a short to battery in the park lamp relay control circuit when it is trying to energize the park lamp relay.
    • The condition above must be present for more than 0.3 seconds.

Action Taken When the DTC Sets

The BCM stores DTC B2588 in memory.

Conditions for Clearing the DTC
    • A short to battery in the park lamp relay control circuit is no longer detected by the BCM when the park lamp relay is commanded to energize. After the fault is removed the ignition must be cycled to clear the code.
    • A history DTC B2588 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 B2588 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 battery positive voltage in the park lamp relay coil control circuit.
       - The park lamp relay coil is shorted to battery positive voltage.
       - The BCM is shorted to battery positive voltage.

Test Description

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

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

    2.

  2. Verifies that the BCM is providing ground to the park lamp relay. Indicating a short to battery positive voltage internal to the park lamp relay.

    3.

  3. Test for a short to battery positive voltage in the control circuit of the park lamp relay.

Step

Action

Yes

No

Schematic Reference: Exterior 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. With a scan tool, command the park lamp relay ON and OFF.

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

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the park lamp relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the control circuit of the park lamp relay and the coil side supply circuit of the park lamp relay.
  5. With a scan tool, command the park lamp relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 5

Go to Step 4

4

Test the control circuit of the park 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 7

Go to Step 6

5

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

Did you complete the replacement?

Go to Step 7

--

6

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

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

Did you complete the replacement?

Go to Step 7

--

7
  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