GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Equinox 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC B2585

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 fuse. The BCM grounds the park lamp relay control circuit in order to activate the relay. With the park lamp relay activated voltage is supplied to the park lamp supply voltage circuit illuminating the park lamps, license lamps, marker lamps, and signaling the BCM.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2585 Park Lamp Circuit

Conditions for Running the DTC
    • The ignition switch is in the RUN position.
    • The ambient light sensor senses a dark condition, automatic lamp control (ALC) park lamps ON, or the headlamp switch is in the park or head ON position.

Conditions for Setting the DTC

Any of the following conditions will set this DTC:

    • The park lamp relay control circuit is open.
    • The park lamp supply voltage circuit is open between the instrument panel (I/P) fuse block and the BCM for 5 seconds.
    • The park lamp supply voltage circuit is shorted to ground.
    • The park lamp relay is stuck in the OPEN position.

Action Taken When the DTC Sets
    • The park lamps will operate properly if the park lamp supply voltage circuit is open between the I/P fuse block and the BCM.
    • The park lamps will not illuminate if relay is stuck open or the PARK fuse in the I/P fuse block is open.

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

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

    3.

  3. Verifies that the BCM is providing ground to the park lamp relay.

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

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 park lamps ON and OFF.

Do the park lamps turn ON and OFF with each command?

Go to Step 5

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the park lamp relay.
  3. Turn ON the ignition, with the engine OFF.
  4. 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 4

Go to Step 9

4

  1. Connect a test lamp between the control circuit of the park lamp relay and the coil side battery positive voltage circuit of the park lamp relay.
  2. 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 6

5

Test for an open or high resistance in the park lamp supply voltage circuit to the body control module (BCM). 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 or high resistance in the control circuit of the park lamp 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 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 12

Go to Step 10

8

Inspect for poor connections at the harness connector of the 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 park lamp relay or the short to ground in the park lamp supply voltage circuit. 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 park lamp relay. Refer to Relay Replacement in Wiring Systems.

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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