GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Express - AWD 🢒 Body Systems 🢒 Lighting 🢒 DTC B2585

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B2585 00: Left Park Lamp Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Park Lamp Relay Control

1

1

B2585 00

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1. Park Lamps Malfunction

Circuit/System Description

Battery positive voltage is applied at all times to both the coil and switched sides of the PRK LAMP relay. The park lamps are controlled by the body control module (BCM) by inputs from park lamp switch. When the BCM receives a park lamps ON command, it grounds the park lamps relay control circuit in order to energize the PRK LAMP relay. With the relay energized, battery voltage is applied through switch side of the relay, both PARK fuses, and the park lamp supply voltage circuits to all park, tail, and marker lamps.

Conditions for Running the DTC

Park lamps ON.

Conditions for Setting the DTC

The BCM detects a short to voltage on the park lamp relay control circuit.

Action Taken When the DTC Sets

The BCM will deactivate the PRK LAMP relay for the remainder of the ignition cycle.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, turn the park lamps on. The park lamps should illuminate.

Circuit/System Testing
  1. Ignition OFF, disconnect the park lamp relay.
  2. Connect a test lamp between the control circuit terminal 86 and B+.
  3. Ignition ON, command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    4. ⇒ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, test or replace the park lamp relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Relay Replacement
    •  Control Module References for BCM replacement, setup, and programming