GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Malibu 🢒 DTC 🢒 DTC B2587

Circuit Description

The body control module (BCM) turns on the park lamp relay when the ambient light sensor senses a dark condition. Battery positive voltage is supplied to the park lamp relay at all times through the PARK LPS fuse. The BCM grounds the park lamp relay control circuit in order to activate the relay.

Conditions for Running the DTC
    • The ignition switch is in the ON position.
    • The ambient light sensor senses a light condition (ALC park lamps off).

Conditions for Setting the DTC
    • The park lamp relay control circuit is shorted to ground or open for 5 seconds.
    • ALC is not in operation.
    • The headlamp switch is not in the PARK position.

Action Taken When the DTC Sets
    • The SERVICE indicator will illuminate.
    • The check gages chime sounds.

Conditions for Clearing the DTC
    • The conditions for setting the DTC are no longer present.
    • A history DTC clears after 100 malfunction free ignition cycles.
    • The BCM receives the clear code command from the scan tool.

Diagnostic Aids

If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

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

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

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 Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Place the headlamp switch in the OFF position.

Are the park lamps illuminated?

Go to Step 6

Go to Step 4

4
  1. Disconnect the ALC park lamp relay.
  2. Probe the coil side battery positive voltage circuit of the park lamp relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

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

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

6

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

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test for an open or high resistance in the park lamp relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

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

Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Repair an open, high resistance, or short to ground in the coil side battery positive voltage circuit of the park lamp relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the ALC park lamp relay.

Did you complete the replacement?

Go to Step 13

--

12

Important: Perform the set up procedure for the body control module.

Replace the body control module. Refer to Body Control Module Replacement .

Did you complete the replacement?

Go to Step 13

--

13
  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