GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Grand Am 🢒 DTC 🢒 DTC B2585

Circuit Description

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

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2585 Parklamp Control Circuit

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

Conditions for Setting the DTC
    • The auto park lamp control relay control circuit is open or shorted to voltage for 5 seconds.
    • The park lamp supply voltage circuit is open or shorted to ground for 5 seconds.

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

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

  2. Tests for voltage at the coil side of the auto park lamp control relay . The PARK LPS fuse supplies battery positive voltage to the coil side of the auto park lamp control relay.

    3.

  3. Verifies that the body control module is providing ground to the auto parklamp control 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 lamps ON and OFF.

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

Does the test lamp illuminate?

Go to Step 4

Go to Step 9

4

  1. Connect a test lamp between the control circuit of the auto park lamp control relay and the coil side battery positive voltage circuit of the auto park lamp control relay.
  2. With a scan tool, command the auto park lamp control relay ON and OFF .

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

Go to Step 5

Go to Step 6

5

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

Did you find and correct the condition?

Go to Step 12

Go to Step 7

6

Test for an open, high resistance, or short to voltage in the control circuit of the auto park lamp control relay. 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

7

Inspect for poor connection at the auto park lamp control 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 12

Go to Step 10

8

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 12

Go to Step 11

9

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

Did you complete the repair?

Go to Step 12

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10

Replace the auto park lamp control relay.

Did you complete the replacement?

Go to Step 12

--

11

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 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

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