GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Classic 🢒 Restraints 🢒 SIR 🢒 DTC B2588

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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2588 Park Lamp Control Circuit High

Conditions for Running the DTC
    • The ignition switch is in the ON position.
    • The ambient light sensor senses a dark condition, park lamps ON.

Conditions for Setting the DTC

The park lamp relay control circuit is shorted to battery positive voltage for 1 second.

Action Taken When the DTC Sets
    • The BCM turns off the park lamps relay control for the remainder of the ignition cycle.
    • The SERVICE indicator illuminates.
    • 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 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. This step tests for voltage at the coil side of the ALC park lamp relay. The PARK LPS fuse supplies power to the coil side of the ALC 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 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 automatic lighting control (ALC) park lamp relay ON and OFF.

Does the ALC 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. Disconnect the ALC parklamp relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side battery positive voltage circuit of the ALC park lamp relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 6

4

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

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

Inspect for poor connections at the harness connector of the body control module (BCM). 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 8

Go to Step 7

6

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

Did you complete the repair?

Go to Step 8

--

7

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 8

--

8
  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